diff --git a/src/server/injected/attributeSelectorEngine.ts b/src/server/injected/attributeSelectorEngine.ts
deleted file mode 100644
index 4965d81acf..0000000000
--- a/src/server/injected/attributeSelectorEngine.ts
+++ /dev/null
@@ -1,66 +0,0 @@
-/**
- * Copyright (c) Microsoft Corporation.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-import { SelectorEngine, SelectorRoot } from './selectorEngine';
-
-export function createAttributeEngine(attribute: string, shadow: boolean): SelectorEngine {
-  const engine: SelectorEngine = {
-    query(root: SelectorRoot, selector: string): Element | undefined {
-      if (!shadow)
-        return root.querySelector(`[${attribute}=${JSON.stringify(selector)}]`) || undefined;
-      return queryShadowInternal(root, attribute, selector);
-    },
-
-    queryAll(root: SelectorRoot, selector: string): Element[] {
-      if (!shadow)
-        return Array.from(root.querySelectorAll(`[${attribute}=${JSON.stringify(selector)}]`));
-      const result: Element[] = [];
-      queryShadowAllInternal(root, attribute, selector, result);
-      return result;
-    }
-  };
-  return engine;
-}
-
-function queryShadowInternal(root: SelectorRoot, attribute: string, value: string): Element | undefined {
-  const single = root.querySelector(`[${attribute}=${JSON.stringify(value)}]`);
-  if (single)
-    return single;
-  const all = root.querySelectorAll('*');
-  for (let i = 0; i < all.length; i++) {
-    const shadowRoot = all[i].shadowRoot;
-    if (shadowRoot) {
-      const single = queryShadowInternal(shadowRoot, attribute, value);
-      if (single)
-        return single;
-    }
-  }
-}
-
-function queryShadowAllInternal(root: SelectorRoot, attribute: string, value: string, result: Element[]) {
-  const document = root instanceof Document ? root : root.ownerDocument;
-  const walker = document.createTreeWalker(root, NodeFilter.SHOW_ELEMENT);
-  const shadowRoots = [];
-  while (walker.nextNode()) {
-    const element = walker.currentNode as Element;
-    if (element.getAttribute(attribute) === value)
-      result.push(element);
-    if (element.shadowRoot)
-      shadowRoots.push(element.shadowRoot);
-  }
-  for (const shadowRoot of shadowRoots)
-    queryShadowAllInternal(shadowRoot, attribute, value, result);
-}
diff --git a/src/server/injected/cssSelectorEngine.ts b/src/server/injected/cssSelectorEngine.ts
deleted file mode 100644
index 4002ac62e8..0000000000
--- a/src/server/injected/cssSelectorEngine.ts
+++ /dev/null
@@ -1,264 +0,0 @@
-/**
- * Copyright (c) Microsoft Corporation.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-import { SelectorEngine, SelectorRoot } from './selectorEngine';
-
-export function createCSSEngine(shadow: boolean): SelectorEngine {
-  const engine: SelectorEngine = {
-    query(root: SelectorRoot, selector: string): Element | undefined {
-      // TODO: uncomment for performance.
-      // const simple = root.querySelector(selector);
-      // if (simple)
-      //   return simple;
-      // if (!shadow)
-      //   return;
-      const selectors = split(selector);
-      // Note: we do not just merge results produced by each selector, as that
-      // will not return them in the tree traversal order, but rather in the selectors
-      // matching order.
-      if (!selectors.length)
-        return;
-      return queryShadowInternal(root, root, selectors, shadow);
-    },
-
-    queryAll(root: SelectorRoot, selector: string): Element[] {
-      // TODO: uncomment for performance.
-      // if (!shadow)
-      //   return Array.from(root.querySelectorAll(selector));
-      const result: Element[] = [];
-      const selectors = split(selector);
-      // Note: we do not just merge results produced by each selector, as that
-      // will not return them in the tree traversal order, but rather in the selectors
-      // matching order.
-      if (selectors.length)
-        queryShadowAllInternal(root, root, selectors, shadow, result);
-      return result;
-    }
-  };
-  (engine as any)._test = () => test(engine);
-  return engine;
-}
-
-function queryShadowInternal(boundary: SelectorRoot, root: SelectorRoot, selectors: string[][], shadow: boolean): Element | undefined {
-  let elements: NodeListOf<Element> | undefined;
-  if (selectors.length === 1) {
-    // Fast path for a single selector - query only matching elements, not all.
-    const parts = selectors[0];
-    const matching = root.querySelectorAll(parts[0]);
-    for (const element of matching) {
-      // If there is a single part, there are no ancestors to match.
-      if (parts.length === 1 || ancestorsMatch(element, parts, boundary))
-        return element;
-    }
-  } else {
-    // Multiple selectors: visit each element in tree-traversal order and check whether it matches.
-    elements = root.querySelectorAll('*');
-    for (const element of elements) {
-      for (const parts of selectors) {
-        if (!element.matches(parts[0]))
-          continue;
-        // If there is a single part, there are no ancestors to match.
-        if (parts.length === 1 || ancestorsMatch(element, parts, boundary))
-          return element;
-      }
-    }
-  }
-
-  // Visit shadow dom after the light dom to preserve the tree-traversal order.
-  if (!shadow)
-    return;
-  if ((root as Element).shadowRoot) {
-    const child = queryShadowInternal(boundary, (root as Element).shadowRoot!, selectors, shadow);
-    if (child)
-      return child;
-  }
-  if (!elements)
-    elements = root.querySelectorAll('*');
-  for (const element of elements) {
-    if (element.shadowRoot) {
-      const child = queryShadowInternal(boundary, element.shadowRoot, selectors, shadow);
-      if (child)
-        return child;
-    }
-  }
-}
-
-function queryShadowAllInternal(boundary: SelectorRoot, root: SelectorRoot, selectors: string[][], shadow: boolean, result: Element[]) {
-  let elements: NodeListOf<Element> | undefined;
-  if (selectors.length === 1) {
-    // Fast path for a single selector - query only matching elements, not all.
-    const parts = selectors[0];
-    const matching = root.querySelectorAll(parts[0]);
-    for (const element of matching) {
-      // If there is a single part, there are no ancestors to match.
-      if (parts.length === 1 || ancestorsMatch(element, parts, boundary))
-        result.push(element);
-    }
-  } else {
-    // Multiple selectors: visit each element in tree-traversal order and check whether it matches.
-    elements = root.querySelectorAll('*');
-    for (const element of elements) {
-      for (const parts of selectors) {
-        if (!element.matches(parts[0]))
-          continue;
-        // If there is a single part, there are no ancestors to match.
-        if (parts.length === 1 || ancestorsMatch(element, parts, boundary))
-          result.push(element);
-      }
-    }
-  }
-
-  // Visit shadow dom after the light dom to preserve the tree-traversal order.
-  if (!shadow)
-    return;
-  if ((root as Element).shadowRoot)
-    queryShadowAllInternal(boundary, (root as Element).shadowRoot!, selectors, shadow, result);
-  if (!elements)
-    elements = root.querySelectorAll('*');
-  for (const element of elements) {
-    if (element.shadowRoot)
-      queryShadowAllInternal(boundary, element.shadowRoot, selectors, shadow, result);
-  }
-}
-
-function ancestorsMatch(element: Element | undefined, parts: string[], boundary: SelectorRoot): boolean {
-  let i = 1;
-  while (i < parts.length && (element = parentElementOrShadowHost(element!)) && element !== boundary) {
-    if (element.matches(parts[i]))
-      i++;
-  }
-  return i === parts.length;
-}
-
-function parentElementOrShadowHost(element: Element): Element | undefined {
-  if (element.parentElement)
-    return element.parentElement;
-  if (!element.parentNode)
-    return;
-  if (element.parentNode.nodeType === Node.DOCUMENT_FRAGMENT_NODE && (element.parentNode as ShadowRoot).host)
-    return (element.parentNode as ShadowRoot).host;
-}
-
-// Splits the string into separate selectors by comma, and then each selector by the descendant combinator (space).
-// Parts of each selector are reversed, so that the first one matches the target element.
-function split(selector: string): string[][] {
-  let index = 0;
-  let quote: string | undefined;
-  let insideAttr = false;
-  let start = 0;
-  const result: string[][] = [];
-  let current: string[] = [];
-  const appendToCurrent = () => {
-    const part = selector.substring(start, index).trim();
-    if (part.length)
-      current.push(part);
-  };
-  const appendToResult = () => {
-    appendToCurrent();
-    result.push(current);
-    current = [];
-  };
-  const isCombinator = (char: string) => {
-    return char === '>' || char === '+' || char === '~';
-  };
-  const peekForward = () => {
-    return selector.substring(index).trim()[0];
-  };
-  const peekBackward = () => {
-    const s = selector.substring(0, index).trim();
-    return s[s.length - 1];
-  };
-  while (index < selector.length) {
-    const c = selector[index];
-    if (!quote && !insideAttr && c === ' ' && !isCombinator(peekForward()) && !isCombinator(peekBackward())) {
-      appendToCurrent();
-      start = index;
-      index++;
-    } else {
-      if (c === '\\' && index + 1 < selector.length) {
-        index += 2;
-      } else if (c === quote) {
-        quote = undefined;
-        index++;
-      } else if (!quote && (c === '\'' || c === '"')) {
-        quote = c;
-        index++;
-      } else if (!quote && c === '[') {
-        insideAttr = true;
-        index++;
-      } else if (!quote && insideAttr && c === ']') {
-        insideAttr = false;
-        index++;
-      } else if (!quote && !insideAttr && c === ',') {
-        appendToResult();
-        index++;
-        start = index;
-      } else {
-        index++;
-      }
-    }
-  }
-  appendToResult();
-  return result.filter(parts => !!parts.length).map(parts => parts.reverse());
-}
-
-function test(engine: SelectorEngine) {
-  let id = 0;
-
-  function createShadow(level: number): Element {
-    const root = document.createElement('div');
-    root.id = 'id' + id;
-    root.textContent = 'root #id' + id;
-    id++;
-    const shadow = root.attachShadow({ mode: 'open' });
-    for (let i = 0; i < 9; i++) {
-      const div = document.createElement('div');
-      div.id = 'id' + id;
-      div.textContent = '#id' + id;
-      id++;
-      shadow.appendChild(div);
-    }
-    if (level) {
-      shadow.appendChild(createShadow(level - 1));
-      shadow.appendChild(createShadow(level - 1));
-    }
-    return root;
-  }
-
-  const {query, queryAll} = engine;
-
-  document.body.textContent = '';
-  document.body.appendChild(createShadow(10));
-  console.time('found');
-  for (let i = 0; i < id; i += 17) {
-    const e = query(document, `div #id${i}`);
-    if (!e || e.id !== 'id' + i)
-      console.log(`div #id${i}`);  // eslint-disable-line no-console
-  }
-  console.timeEnd('found');
-  console.time('not found');
-  for (let i = 0; i < id; i += 17) {
-    const e = query(document, `div div div div div #d${i}`);
-    if (e)
-      console.log(`div div div div div #d${i}`);  // eslint-disable-line no-console
-  }
-  console.timeEnd('not found');
-  console.log(query(document, '#id543 + #id544'));  // eslint-disable-line no-console
-  console.log(query(document, '#id542 ~ #id545'));  // eslint-disable-line no-console
-  console.time('all');
-  queryAll(document, 'div div div + div');
-  console.timeEnd('all');
-}
diff --git a/src/server/injected/injectedScript.ts b/src/server/injected/injectedScript.ts
index ee30eb4941..aeac733c96 100644
--- a/src/server/injected/injectedScript.ts
+++ b/src/server/injected/injectedScript.ts
@@ -14,14 +14,13 @@
  * limitations under the License.
  */
 
-import { createAttributeEngine } from './attributeSelectorEngine';
 import { SelectorEngine, SelectorRoot } from './selectorEngine';
 import { createTextSelector } from './textSelectorEngine';
 import { XPathEngine } from './xpathSelectorEngine';
 import { ParsedSelector, ParsedSelectorPart, parseSelector } from '../common/selectorParser';
 import { FatalDOMError } from '../common/domErrors';
 import { SelectorEvaluatorImpl, isVisible, parentElementOrShadowHost } from './selectorEvaluator';
-import { createCSSEngine } from './cssSelectorEngine';
+import { CSSComplexSelectorList } from '../common/cssParser';
 
 type Predicate<T> = (progress: InjectedScriptProgress, continuePolling: symbol) => T | symbol;
 
@@ -46,20 +45,18 @@ export class InjectedScript {
 
   constructor(customEngines: { name: string, engine: SelectorEngine}[]) {
     this._enginesV1 = new Map();
-    this._enginesV1.set('css', createCSSEngine(true));
-    this._enginesV1.set('css:light', createCSSEngine(false));
     this._enginesV1.set('xpath', XPathEngine);
     this._enginesV1.set('xpath:light', XPathEngine);
     this._enginesV1.set('text', createTextSelector(true));
     this._enginesV1.set('text:light', createTextSelector(false));
-    this._enginesV1.set('id', createAttributeEngine('id', true));
-    this._enginesV1.set('id:light', createAttributeEngine('id', false));
-    this._enginesV1.set('data-testid', createAttributeEngine('data-testid', true));
-    this._enginesV1.set('data-testid:light', createAttributeEngine('data-testid', false));
-    this._enginesV1.set('data-test-id', createAttributeEngine('data-test-id', true));
-    this._enginesV1.set('data-test-id:light', createAttributeEngine('data-test-id', false));
-    this._enginesV1.set('data-test', createAttributeEngine('data-test', true));
-    this._enginesV1.set('data-test:light', createAttributeEngine('data-test', false));
+    this._enginesV1.set('id', this._createAttributeEngine('id', true));
+    this._enginesV1.set('id:light', this._createAttributeEngine('id', false));
+    this._enginesV1.set('data-testid', this._createAttributeEngine('data-testid', true));
+    this._enginesV1.set('data-testid:light', this._createAttributeEngine('data-testid', false));
+    this._enginesV1.set('data-test-id', this._createAttributeEngine('data-test-id', true));
+    this._enginesV1.set('data-test-id:light', this._createAttributeEngine('data-test-id', false));
+    this._enginesV1.set('data-test', this._createAttributeEngine('data-test', true));
+    this._enginesV1.set('data-test:light', this._createAttributeEngine('data-test', false));
     for (const { name, engine } of customEngines)
       this._enginesV1.set(name, engine);
 
@@ -133,6 +130,21 @@ export class InjectedScript {
     return this._enginesV1.get(part.name)!.queryAll(root, part.body);
   }
 
+  private _createAttributeEngine(attribute: string, shadow: boolean): SelectorEngine {
+    const toCSS = (selector: string): CSSComplexSelectorList => {
+      const css = `[${attribute}=${JSON.stringify(selector)}]`;
+      return [{ simples: [{ selector: { css, functions: [] }, combinator: '' }] }];
+    };
+    return {
+      query: (root: SelectorRoot, selector: string): Element | undefined => {
+        return this._evaluator.evaluate({ scope: root as Document | Element, pierceShadow: shadow }, toCSS(selector))[0];
+      },
+      queryAll: (root: SelectorRoot, selector: string): Element[] => {
+        return this._evaluator.evaluate({ scope: root as Document | Element, pierceShadow: shadow }, toCSS(selector));
+      }
+    };
+  }
+
   extend(source: string, params: any): any {
     const constrFunction = global.eval(source);
     return new constrFunction(this, params);
diff --git a/src/server/selectors.ts b/src/server/selectors.ts
index df105e0a04..f241ff00a8 100644
--- a/src/server/selectors.ts
+++ b/src/server/selectors.ts
@@ -31,7 +31,7 @@ export class Selectors {
   readonly _engines: Map<string, { source: string, contentScript: boolean }>;
 
   constructor() {
-    // Note: keep in sync with SelectorEvaluator class.
+    // Note: keep in sync with InjectedScript class.
     this._builtinEngines = new Set([
       'css', 'css:light',
       'xpath', 'xpath:light',