diff --git a/Lib/test/libregrtest/runtest.py b/Lib/test/libregrtest/runtest.py
index 8ca7b8bb6526ca..e73a8f1a855dc1 100644
--- a/Lib/test/libregrtest/runtest.py
+++ b/Lib/test/libregrtest/runtest.py
@@ -341,11 +341,10 @@ def _load_run_test(result: TestResult, ns: Namespace) -> None:
 
     the_module = importlib.import_module(abstest)
 
-    # If the test has a test_main, that will run the appropriate
-    # tests.  If not, use normal unittest test loading.
-    test_func = getattr(the_module, "test_main", None)
-    if test_func is None:
-        test_func = functools.partial(_test_module, the_module)
+    if hasattr(the_module, "test_main"):
+        # https://github.com/python/cpython/issues/89392
+        raise Exception(f"Module {result.test_name} defines test_main() which is no longer supported by regrtest")
+    test_func = functools.partial(_test_module, the_module)
 
     try:
         with save_env(ns, result.test_name):
diff --git a/Lib/test/test_regrtest.py b/Lib/test/test_regrtest.py
index 8b7599bcb931fe..88c59b79dd5a91 100644
--- a/Lib/test/test_regrtest.py
+++ b/Lib/test/test_regrtest.py
@@ -1680,9 +1680,9 @@ def my_function():
                 7948648
                 """
 
-            def test_main():
-                testmod = sys.modules[__name__]
-                return support.run_doctest(testmod)
+            def load_tests(loader, tests, pattern):
+                tests.addTest(doctest.DocTestSuite())
+                return tests
         ''')
         testname = self.create_test(code=code)
 
@@ -1691,7 +1691,7 @@ def test_main():
         self.check_executed_tests(output, [testname],
                                   failed=[testname],
                                   randomize=True,
-                                  stats=TestStats(3, 2, 0))
+                                  stats=TestStats(1, 1, 0))
 
 
 class TestUtils(unittest.TestCase):
diff --git a/Misc/NEWS.d/next/Tests/2023-09-04-15-18-14.gh-issue-89392.8A4T5p.rst b/Misc/NEWS.d/next/Tests/2023-09-04-15-18-14.gh-issue-89392.8A4T5p.rst
new file mode 100644
index 00000000000000..e1dea8e78cdd4e
--- /dev/null
+++ b/Misc/NEWS.d/next/Tests/2023-09-04-15-18-14.gh-issue-89392.8A4T5p.rst
@@ -0,0 +1,2 @@
+Removed support of ``test_main()`` function in tests. They now always use
+normal unittest test runner.