diff --git a/ChangeLog-11.3.md b/ChangeLog-11.3.md
index 6101b7a580a..59682c7c826 100644
--- a/ChangeLog-11.3.md
+++ b/ChangeLog-11.3.md
@@ -10,6 +10,7 @@ All notable changes of the PHPUnit 11.3 release series are documented in this fi
 * [#4625](https://github.com/sebastianbergmann/phpunit/issues/4625): Generator yielding keys that are neither integer or string leads to hard-to-understand error message when used as data provider
 * [#4674](https://github.com/sebastianbergmann/phpunit/issues/4674): JSON assertions should treat objects as unordered
 * [#5929](https://github.com/sebastianbergmann/phpunit/issues/5929): TestDox output containing `$` at the beginning gets truncated when used with a data provider
+* [#5943](https://github.com/sebastianbergmann/phpunit/issues/5943): Tests configured to be in group(s) using the XML configuration file are also added to the `default` group
 
 ## [11.3.3] - 2024-09-04
 
diff --git a/src/Metadata/Api/Groups.php b/src/Metadata/Api/Groups.php
index 4b88eb2e8c0..71c3c7e5d18 100644
--- a/src/Metadata/Api/Groups.php
+++ b/src/Metadata/Api/Groups.php
@@ -59,10 +59,6 @@ public function groups(string $className, string $methodName, bool $includeVirtu
             $groups[] = $group->groupName();
         }
 
-        if ($groups === []) {
-            $groups[] = 'default';
-        }
-
         if (!$includeVirtual) {
             return self::$groupCache[$key] = array_unique($groups);
         }
diff --git a/tests/end-to-end/regression/5943.phpt b/tests/end-to-end/regression/5943.phpt
new file mode 100644
index 00000000000..d1ed1bfb5d5
--- /dev/null
+++ b/tests/end-to-end/regression/5943.phpt
@@ -0,0 +1,20 @@
+--TEST--
+https://github.com/sebastianbergmann/phpunit/issues/5943
+--FILE--
+<?php declare(strict_types=1);
+$_SERVER['argv'][] = '--do-not-cache-result';
+$_SERVER['argv'][] = '--configuration';
+$_SERVER['argv'][] = __DIR__ . '/5943';
+$_SERVER['argv'][] = '--list-groups';
+
+require_once __DIR__ . '/../../bootstrap.php';
+
+(new PHPUnit\TextUI\Application)->run($_SERVER['argv']);
+--EXPECTF--
+PHPUnit %s by Sebastian Bergmann and contributors.
+
+Available test group(s):
+ - bar
+ - barbara
+ - baz
+ - foo
diff --git a/tests/end-to-end/regression/5943/phpunit.xml b/tests/end-to-end/regression/5943/phpunit.xml
new file mode 100644
index 00000000000..bb66b5abc66
--- /dev/null
+++ b/tests/end-to-end/regression/5943/phpunit.xml
@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:noNamespaceSchemaLocation="../../../../phpunit.xsd"
+>
+    <testsuites>
+        <testsuite name="default">
+            <directory groups="foo,baz">tests/a</directory>
+            <directory groups="bar,barbara">tests/b</directory>
+        </testsuite>
+    </testsuites>
+</phpunit>
diff --git a/tests/end-to-end/regression/5943/tests/a/OneTest.php b/tests/end-to-end/regression/5943/tests/a/OneTest.php
new file mode 100644
index 00000000000..1b5ead72569
--- /dev/null
+++ b/tests/end-to-end/regression/5943/tests/a/OneTest.php
@@ -0,0 +1,20 @@
+<?php declare(strict_types=1);
+/*
+ * This file is part of PHPUnit.
+ *
+ * (c) Sebastian Bergmann <sebastian@phpunit.de>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+namespace PHPUnit\TestFixture\Issue5943;
+
+use PHPUnit\Framework\TestCase;
+
+final class OneTest extends TestCase
+{
+    public function testOne(): void
+    {
+        $this->assertTrue(true);
+    }
+}
diff --git a/tests/end-to-end/regression/5943/tests/b/TwoTest.php b/tests/end-to-end/regression/5943/tests/b/TwoTest.php
new file mode 100644
index 00000000000..6479eacece7
--- /dev/null
+++ b/tests/end-to-end/regression/5943/tests/b/TwoTest.php
@@ -0,0 +1,20 @@
+<?php declare(strict_types=1);
+/*
+ * This file is part of PHPUnit.
+ *
+ * (c) Sebastian Bergmann <sebastian@phpunit.de>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+namespace PHPUnit\TestFixture\Issue5943;
+
+use PHPUnit\Framework\TestCase;
+
+final class TwoTest extends TestCase
+{
+    public function testTwo(): void
+    {
+        $this->assertTrue(true);
+    }
+}
diff --git a/tests/unit/Metadata/Api/GroupsTest.php b/tests/unit/Metadata/Api/GroupsTest.php
index cee6175210e..08ff574e84c 100644
--- a/tests/unit/Metadata/Api/GroupsTest.php
+++ b/tests/unit/Metadata/Api/GroupsTest.php
@@ -30,7 +30,6 @@ public static function provider(): array
         return [
             [
                 [
-                    'default',
                 ],
                 NoGroupsMetadataTest::class,
                 'testOne',