diff --git a/airflow-core/src/airflow/models/taskinstance.py b/airflow-core/src/airflow/models/taskinstance.py
index 8522697c21c1f..2c794a709895f 100644
--- a/airflow-core/src/airflow/models/taskinstance.py
+++ b/airflow-core/src/airflow/models/taskinstance.py
@@ -2316,9 +2316,17 @@ def _visit_relevant_relatives_for_normal(task_ids: Iterable[str]) -> None:
         visited.update(partial_dag.task_dict)
 
     def _visit_relevant_relatives_for_mapped(mapped_tasks: Iterable[tuple[str, int]]) -> None:
+        from airflow.exceptions import NotMapped
+
         for task_id, map_index in mapped_tasks:
             task = dag.get_task(task_id)
-            ti_count = get_mapped_ti_count(task, run_id, session=session)
+            try:
+                ti_count = get_mapped_ti_count(task, run_id, session=session)
+            except NotMapped:
+                # Task is not actually mapped (not a MappedOperator and not inside a mapped task group).
+                # Treat it as a normal task instead.
+                _visit_relevant_relatives_for_normal([task_id])
+                continue
             # TODO (GH-52141): This should return scheduler operator types, but
             # currently get_flat_relatives is inherited from SDK DAGNode.
             relatives = cast("Iterable[Operator]", task.get_flat_relatives(upstream=direction == "upstream"))
diff --git a/airflow-core/tests/unit/models/test_taskinstance.py b/airflow-core/tests/unit/models/test_taskinstance.py
index 3a5ff369e9bd0..ef8122de39e29 100644
--- a/airflow-core/tests/unit/models/test_taskinstance.py
+++ b/airflow-core/tests/unit/models/test_taskinstance.py
@@ -3239,6 +3239,31 @@ def g(v):
     assert result == expected
 
 
+def test_find_relevant_relatives_with_non_mapped_task_as_tuple(dag_maker, session):
+    """Test that specifying a non-mapped task as a tuple doesn't raise NotMapped exception."""
+    # t1 -> t2 (non-mapped) -> t3
+    with dag_maker(session=session) as dag:
+        t1 = EmptyOperator(task_id="t1")
+        t2 = EmptyOperator(task_id="t2")
+        t3 = EmptyOperator(task_id="t3")
+        t1 >> t2 >> t3
+
+    dr = dag_maker.create_dagrun(state="success")
+
+    # Specifying t2 as a tuple (t2, 0) even though it's not mapped should not raise NotMapped
+    # It should treat t2 as a normal task and return its upstream t1
+    result = find_relevant_relatives(
+        normal_tasks=[],
+        mapped_tasks=[("t2", 0)],
+        direction="upstream",
+        dag=dag,
+        run_id=dr.run_id,
+        session=session,
+    )
+    # Should return t1 as the upstream of t2
+    assert result == {"t1"}
+
+
 def test_when_dag_run_has_partition_then_asset_does(dag_maker, session):
     asset = Asset(name="hello")
     with dag_maker(dag_id="asset_event_tester", schedule=None) as dag: