diff --git a/testing/web-platform/tests/event-timing/orphan-keydown.html b/testing/web-platform/tests/event-timing/orphan-keydown.html
new file mode 100644
index 000000000000..0ab105d4d728
--- /dev/null
+++ b/testing/web-platform/tests/event-timing/orphan-keydown.html
@@ -0,0 +1,34 @@
+<!DOCTYPE html>
+<html>
+<meta charset=utf-8 />
+<title>Event Timing: orphan keydown.</title>
+<script src=/resources/testharness.js></script>
+<script src=/resources/testharnessreport.js></script>
+<script src=/resources/testdriver.js></script>
+<script src=/resources/testdriver-actions.js></script>
+<script src=/resources/testdriver-vendor.js></script>
+<script src=resources/event-timing-test-utils.js></script>
+
+<body>
+  <button id='target'>Click me</button>
+
+  <script>
+    let observedEntries = [];
+    const map = new Map();
+    const events = ['keydown'];
+
+    promise_test(async t => {
+      assert_implements(window.PerformanceEventTiming, 'Event Timing is not supported.');
+
+      const callback = (entryList) => {observedEntries = observedEntries.concat(entryList.getEntries().filter(filterAndAddToMap(events, map))); };
+      const readyToResolve = () => { return observedEntries.length >= 1; };
+      const observerPromise = createPerformanceObserverPromise(['event'], callback, readyToResolve);
+
+      await interactAndObserve('orphan-keydown', document.getElementById('target'), observerPromise);
+
+      assert_equals(observedEntries.length, 1, "Keydown without a keyup should be fired properly.");
+      assert_greater_than(map.get('keydown'), 0, "Should have a non-trivial interactionId.")
+    }, "Event Timing: Orphan keydown should be measured as an interaction.");
+  </script>
+</body>
+</html>
diff --git a/testing/web-platform/tests/event-timing/resources/event-timing-test-utils.js b/testing/web-platform/tests/event-timing/resources/event-timing-test-utils.js
index 59c78ebf39c8..afad67bb6fc2 100644
--- a/testing/web-platform/tests/event-timing/resources/event-timing-test-utils.js
+++ b/testing/web-platform/tests/event-timing/resources/event-timing-test-utils.js
@@ -554,6 +554,17 @@ async function interactAndObserve(interactionType, target, observerPromise, key
       interactionPromise = textSelectionAndBlockMain(target, 30);
       break;
     }
+    case 'orphan-keydown': {
+      addListeners(target, ['keydown']);
+      interactionPromise = new test_driver.Actions()
+        .pointerMove(0, 0, {origin: target})
+        .pointerDown()
+        .pointerUp()
+        .addTick()
+        .keyDown('a')
+        .send();
+      break;
+    }
   }
   return Promise.all([interactionPromise, observerPromise]);
 }
