diff --git a/CHANGES b/CHANGES
index a5796204765..6ef683b8e7a 100644
--- a/CHANGES
+++ b/CHANGES
@@ -23,6 +23,8 @@ Bugs fixed
   decorated by functools.lru_cache
 * #9879: autodoc: AttributeError is raised on building document for an object
   having invalid __doc__ atribute
+* #9872: html: Class namespace collision between autodoc signatures and
+  docutils-0.17
 * #9864: mathjax: Failed to render equations via MathJax v2.  The loading method
   of MathJax is back to "async" method again
 
diff --git a/sphinx/writers/html5.py b/sphinx/writers/html5.py
index 15fd1544921..bba07f4478e 100644
--- a/sphinx/writers/html5.py
+++ b/sphinx/writers/html5.py
@@ -13,7 +13,7 @@
 import re
 import urllib.parse
 import warnings
-from typing import TYPE_CHECKING, Iterable, Tuple, cast
+from typing import TYPE_CHECKING, Iterable, Set, Tuple, cast
 
 from docutils import nodes
 from docutils.nodes import Element, Node, Text
@@ -56,6 +56,10 @@ class HTML5Translator(SphinxTranslator, BaseTranslator):
     """
 
     builder: "StandaloneHTMLBuilder" = None
+    # Override docutils.writers.html5_polyglot:HTMLTranslator
+    # otherwise, nodes like <inline classes="s">...</inline> will be
+    # converted to <s>...</s> by `visit_inline`.
+    supported_inline_tags: Set[str] = set()
 
     def __init__(self, document: nodes.document, builder: Builder) -> None:
         super().__init__(document, builder)