diff --git a/src/_pytest/fixtures.py b/src/_pytest/fixtures.py
index dd37f8ec3..923254053 100644
--- a/src/_pytest/fixtures.py
+++ b/src/_pytest/fixtures.py
@@ -682,9 +682,12 @@ class TopRequest(FixtureRequest):
 
     def _fillfixtures(self) -> None:
         item = self._pyfuncitem
-        for argname in item.fixturenames:
-            if argname not in item.funcargs:
-                item.funcargs[argname] = self.getfixturevalue(argname)
+        fixturenames = getattr(item, "fixturenames", self.fixturenames)
+        initialnames = item._fixtureinfo.initialnames
+        for argname in fixturenames:
+            value = self.getfixturevalue(argname)
+            if argname not in item.funcargs and argname in initialnames:
+                item.funcargs[argname] = value
 
     def addfinalizer(self, finalizer: Callable[[], object]) -> None:
         self.node.addfinalizer(finalizer)
diff --git a/testing/python/fixtures.py b/testing/python/fixtures.py
index 81aa2bcc7..c976b656d 100644
--- a/testing/python/fixtures.py
+++ b/testing/python/fixtures.py
@@ -9,7 +9,6 @@ from _pytest.config import ExitCode
 from _pytest.fixtures import deduplicate_names
 from _pytest.fixtures import TopRequest
 from _pytest.monkeypatch import MonkeyPatch
-from _pytest.pytester import get_public_names
 from _pytest.pytester import Pytester
 from _pytest.python import Function
 
@@ -128,8 +127,7 @@ class TestFillFixtures:
         assert isinstance(item, Function)
         # Execute's item's setup, which fills fixtures.
         item.session._setupstate.setup(item)
-        del item.funcargs["request"]
-        assert len(get_public_names(item.funcargs)) == 2
+        assert len(item.funcargs) == 2
         assert item.funcargs["some"] == "test_func"
         assert item.funcargs["other"] == 42
 
@@ -841,8 +839,7 @@ class TestRequestBasic:
         val2 = req.getfixturevalue("other")  # see about caching
         assert val2 == 2
         assert item.funcargs["something"] == 1
-        assert len(get_public_names(item.funcargs)) == 2
-        assert "request" in item.funcargs
+        assert len(item.funcargs) == 1
 
     def test_request_addfinalizer(self, pytester: Pytester) -> None:
         item = pytester.getitem(