diff --git a/docs/src/test-api/class-testconfig.md b/docs/src/test-api/class-testconfig.md
index ab15bbda11..24736de921 100644
--- a/docs/src/test-api/class-testconfig.md
+++ b/docs/src/test-api/class-testconfig.md
@@ -517,7 +517,7 @@ export default defineConfig({
 
 Only the files matching one of these patterns are executed as test files. Matching is performed against the absolute file path. Strings are treated as glob patterns.
 
-By default, Playwright Test looks for files matching `.*(test|spec)\.(js|ts|mjs)`.
+By default, Playwright looks for files matching the following glob pattern: `**/?(*.)@(spec|test).?(m)[jt]s?(x)`. This means JavaScript or TypeScript files with `".test"` or `".spec"` suffix, for example `login-screen.spec.ts`.
 
 **Usage**
 
diff --git a/docs/src/test-api/class-testproject.md b/docs/src/test-api/class-testproject.md
index bf5491adc7..5104510983 100644
--- a/docs/src/test-api/class-testproject.md
+++ b/docs/src/test-api/class-testproject.md
@@ -263,7 +263,7 @@ Use [`property: TestConfig.testIgnore`] to change this option for all projects.
 
 Only the files matching one of these patterns are executed as test files. Matching is performed against the absolute file path. Strings are treated as glob patterns.
 
-By default, Playwright Test looks for files matching `.*(test|spec)\.(js|ts|mjs)`.
+By default, Playwright looks for files matching the following glob pattern: `**/?(*.)@(spec|test).?(m)[jt]s?(x)`. This means JavaScript or TypeScript files with `".test"` or `".spec"` suffix, for example `login-screen.spec.ts`.
 
 Use [`property: TestConfig.testMatch`] to change this option for all projects.
 
diff --git a/packages/playwright-test/src/common/configLoader.ts b/packages/playwright-test/src/common/configLoader.ts
index 024ca929c9..40ef762241 100644
--- a/packages/playwright-test/src/common/configLoader.ts
+++ b/packages/playwright-test/src/common/configLoader.ts
@@ -234,7 +234,7 @@ export class ConfigLoader {
       snapshotDir,
       snapshotPathTemplate,
       testIgnore: takeFirst(projectConfig.testIgnore, config.testIgnore, []),
-      testMatch: takeFirst(projectConfig.testMatch, config.testMatch, '**/?(*.)@(spec|test).*'),
+      testMatch: takeFirst(projectConfig.testMatch, config.testMatch, '**/?(*.)@(spec|test).?(m)[jt]s?(x)'),
       timeout: takeFirst(projectConfig.timeout, config.timeout, defaultTimeout),
       use: mergeObjects(config.use, projectConfig.use),
       dependencies: projectConfig.dependencies || [],
diff --git a/packages/playwright-test/types/test.d.ts b/packages/playwright-test/types/test.d.ts
index e2834a7a90..3689130dd6 100644
--- a/packages/playwright-test/types/test.d.ts
+++ b/packages/playwright-test/types/test.d.ts
@@ -347,7 +347,8 @@ export interface FullProject<TestArgs = {}, WorkerArgs = {}> {
    * Only the files matching one of these patterns are executed as test files. Matching is performed against the
    * absolute file path. Strings are treated as glob patterns.
    *
-   * By default, Playwright Test looks for files matching `.*(test|spec)\.(js|ts|mjs)`.
+   * By default, Playwright looks for files matching the following glob pattern: `**\/?(*.)@(spec|test).?(m)[jt]s?(x)`.
+   * This means JavaScript or TypeScript files with `".test"` or `".spec"` suffix, for example `login-screen.spec.ts`.
    *
    * Use [testConfig.testMatch](https://playwright.dev/docs/api/class-testconfig#test-config-test-match) to change this
    * option for all projects.
@@ -1190,7 +1191,8 @@ interface TestConfig {
    * Only the files matching one of these patterns are executed as test files. Matching is performed against the
    * absolute file path. Strings are treated as glob patterns.
    *
-   * By default, Playwright Test looks for files matching `.*(test|spec)\.(js|ts|mjs)`.
+   * By default, Playwright looks for files matching the following glob pattern: `**\/?(*.)@(spec|test).?(m)[jt]s?(x)`.
+   * This means JavaScript or TypeScript files with `".test"` or `".spec"` suffix, for example `login-screen.spec.ts`.
    *
    * **Usage**
    *
@@ -5853,7 +5855,8 @@ interface TestProject {
    * Only the files matching one of these patterns are executed as test files. Matching is performed against the
    * absolute file path. Strings are treated as glob patterns.
    *
-   * By default, Playwright Test looks for files matching `.*(test|spec)\.(js|ts|mjs)`.
+   * By default, Playwright looks for files matching the following glob pattern: `**\/?(*.)@(spec|test).?(m)[jt]s?(x)`.
+   * This means JavaScript or TypeScript files with `".test"` or `".spec"` suffix, for example `login-screen.spec.ts`.
    *
    * Use [testConfig.testMatch](https://playwright.dev/docs/api/class-testconfig#test-config-test-match) to change this
    * option for all projects.
diff --git a/tests/playwright-test/loader.spec.ts b/tests/playwright-test/loader.spec.ts
index 53b949ed6a..0129f7202f 100644
--- a/tests/playwright-test/loader.spec.ts
+++ b/tests/playwright-test/loader.spec.ts
@@ -689,3 +689,18 @@ test('should support dynamic import', async ({ runInlineTest, nodeVersion }) =>
   expect(result.passed).toBe(2);
   expect(result.exitCode).toBe(0);
 });
+
+test('should allow test.extend.ts file', async ({ runInlineTest }) => {
+  const result = await runInlineTest({
+    'test.extend.ts': `
+      export { test, expect } from '@playwright/test';
+    `,
+    'a.test.ts': `
+      import { test, expect } from './test.extend';
+      test('pass1', async () => {
+      });
+    `,
+  });
+  expect(result.exitCode).toBe(0);
+  expect(result.passed).toBe(1);
+});