diff --git a/libraries/exoplayer_ima/src/main/java/androidx/media3/exoplayer/ima/ImaUtil.java b/libraries/exoplayer_ima/src/main/java/androidx/media3/exoplayer/ima/ImaUtil.java
index 90fbeea96d..60ae1cd4b7 100644
--- a/libraries/exoplayer_ima/src/main/java/androidx/media3/exoplayer/ima/ImaUtil.java
+++ b/libraries/exoplayer_ima/src/main/java/androidx/media3/exoplayer/ima/ImaUtil.java
@@ -421,6 +421,7 @@ import java.util.Set;
     Map<Object, AdPlaybackState> adPlaybackStates = new HashMap<>();
     for (int i = adPlaybackState.removedAdGroupCount; i < adPlaybackState.adGroupCount; i++) {
       AdGroup adGroup = adPlaybackState.getAdGroup(/* adGroupIndex= */ i);
+      int mappedAdCount = 0;
       if (adGroup.timeUs == C.TIME_END_OF_SOURCE) {
         checkState(i == adPlaybackState.adGroupCount - 1);
         // The last ad group is a placeholder for a potential post roll. We can just stop here.
@@ -454,8 +455,10 @@ import java.util.Set;
                     adsId, adGroup, periodStartUs, periodDurationUs, window.isLive()));
             // Current period added as an ad period. Advance and look at the next period.
             periodIndex++;
+            mappedAdCount++;
             elapsedAdGroupAdDurationUs += periodDurationUs;
-            if (periodStartUs + periodDurationUs == adGroup.timeUs + adGroupDurationUs) {
+            if ((adGroup.originalCount > adGroup.count && adGroup.count == mappedAdCount)
+                || periodStartUs + periodDurationUs == adGroup.timeUs + adGroupDurationUs) {
               // Periods have consumed the ad group. We're at the end of the ad group.
               if (window.isLive()) {
                 // Add elapsed ad duration to elapsed content duration for live streams to account
diff --git a/libraries/exoplayer_ima/src/test/java/androidx/media3/exoplayer/ima/ImaUtilTest.java b/libraries/exoplayer_ima/src/test/java/androidx/media3/exoplayer/ima/ImaUtilTest.java
index d0bf367819..e7c694bce5 100644
--- a/libraries/exoplayer_ima/src/test/java/androidx/media3/exoplayer/ima/ImaUtilTest.java
+++ b/libraries/exoplayer_ima/src/test/java/androidx/media3/exoplayer/ima/ImaUtilTest.java
@@ -853,6 +853,46 @@ public class ImaUtilTest {
     assertThat(adPlaybackStates.get("uid-14[a]").adGroupCount).isEqualTo(2);
   }
 
+  @Test
+  public void
+      splitAdPlaybackStateForPeriods_partialAdGroupEndingAtPeriodBeforeLast_adPeriodsCorrectlyDetected() {
+    AdPlaybackState adPlaybackState =
+        new AdPlaybackState(/* adsId= */ "adsId", C.TIME_END_OF_SOURCE)
+            .withIsServerSideInserted(/* adGroupIndex= */ 0, true);
+    FakeMultiPeriodLiveTimeline liveTimeline =
+        new FakeMultiPeriodLiveTimeline(
+            /* availabilityStartTimeMs= */ 0,
+            /* liveWindowDurationUs= */ 60_000_000,
+            /* nowUs= */ 70_000_000,
+            /* adSequencePattern= */ new boolean[] {false, true, true, true},
+            /* periodDurationMsPattern= */ new long[] {30_000, 10_000, 10_000, 10_000},
+            /* isContentTimeline= */ true,
+            /* populateAds= */ false,
+            /* playedAds= */ false);
+    // Ad event received from SDK around 30s.
+    adPlaybackState =
+        addLiveAdBreak(
+            /* currentContentPeriodPositionUs= */ 40_000_000,
+            /* adDurationUs= */ 10_000_000,
+            /* adPositionInAdPod= */ 2,
+            /* totalAdDurationUs= */ 30_000_000,
+            /* totalAdsInAdPod= */ 3,
+            adPlaybackState);
+
+    ImmutableMap<Object, AdPlaybackState> splitAdPlaybackStates =
+        ImaUtil.splitAdPlaybackStateForPeriods(adPlaybackState, liveTimeline);
+
+    assertThat(liveTimeline.getPeriodCount()).isEqualTo(5);
+    assertThat(splitAdPlaybackStates).hasSize(5);
+    assertThat(liveTimeline.getWindow(0, new Window()).windowStartTimeMs).isEqualTo(10_000L);
+    assertThat(liveTimeline.getPeriod(0, new Period()).positionInWindowUs).isEqualTo(-10_000_000L);
+    assertThat(splitAdPlaybackStates.get("uid-0[c]").adGroupCount).isEqualTo(1);
+    assertThat(splitAdPlaybackStates.get("uid-1[a]").adGroupCount).isEqualTo(1);
+    assertThat(splitAdPlaybackStates.get("uid-2[a]").adGroupCount).isEqualTo(2);
+    assertThat(splitAdPlaybackStates.get("uid-3[a]").adGroupCount).isEqualTo(2);
+    assertThat(splitAdPlaybackStates.get("uid-4[c]").adGroupCount).isEqualTo(1);
+  }
+
   @Test
   public void
       splitAdPlaybackStateForPeriods_fullAdGroupAtBeginOfWindow_adPeriodsCorrectlyDetected() {