diff --git a/lobby/tests.py b/lobby/tests.py
index 6722cf5..5ee08e1 100644
--- a/lobby/tests.py
+++ b/lobby/tests.py
@@ -1399,10 +1399,19 @@ class RevealRoundFlowTests(TestCase):
         mock_sync_broadcast_phase_event.assert_called_once()
         self.assertEqual(mock_sync_broadcast_phase_event.call_args.args[1], "phase.lie_started")
 
-    def test_start_next_round_rejects_plain_first_round_lie_phase(self):
+    def test_start_next_round_rejects_plain_lie_phase_without_prior_scoreboard_transition(self):
         self.client.login(username="host_reveal", password="secret123")
+        ScoreEvent.objects.filter(session=self.session).delete()
         self.session.status = GameSession.Status.LIE
-        self.session.save(update_fields=["status"])
+        self.session.current_round = 2
+        self.session.save(update_fields=["status", "current_round"])
+        RoundConfig.objects.create(session=self.session, number=2, category=self.category)
+        RoundQuestion.objects.create(
+            session=self.session,
+            round_number=2,
+            question=self.next_question,
+            correct_answer=self.next_question.correct_answer,
+        )
 
         response = self.client.post(
             reverse(
@@ -1416,9 +1425,11 @@ class RevealRoundFlowTests(TestCase):
         self.assertEqual(response.json()["error_code"], "next_round_invalid_phase")
         self.session.refresh_from_db()
         self.assertEqual(self.session.status, GameSession.Status.LIE)
-        self.assertEqual(self.session.current_round, 1)
+        self.assertEqual(self.session.current_round, 2)
         self.assertEqual(RoundConfig.objects.filter(session=self.session, number=1).count(), 1)
+        self.assertEqual(RoundConfig.objects.filter(session=self.session, number=2).count(), 1)
         self.assertEqual(RoundQuestion.objects.filter(session=self.session, round_number=1).count(), 1)
+        self.assertEqual(RoundQuestion.objects.filter(session=self.session, round_number=2).count(), 1)
 
     def test_start_next_round_clears_existing_next_round_bootstrap_state(self):
         self.client.login(username="host_reveal", password="secret123")
diff --git a/lobby/views.py b/lobby/views.py
index 64aa0b0..222fe1e 100644
--- a/lobby/views.py
+++ b/lobby/views.py
@@ -1135,6 +1135,25 @@ def start_next_round(request: HttpRequest, code: str) -> JsonResponse:
             if locked_session.current_round <= 1:
                 return api_error(request, code="next_round_invalid_phase", status=400)
 
+            previous_round_question = RoundQuestion.objects.filter(
+                session=locked_session,
+                round_number=locked_session.current_round - 1,
+            ).first()
+            if previous_round_question is None:
+                return api_error(request, code="next_round_invalid_phase", status=400)
+
+            previous_round_players_count = Player.objects.filter(session=locked_session).count()
+            previous_round_guess_count = Guess.objects.filter(round_question=previous_round_question).count()
+            previous_round_has_score_events = ScoreEvent.objects.filter(
+                session=locked_session,
+                meta__round_question_id=previous_round_question.id,
+            ).exists()
+            previous_round_reveal_resolved = previous_round_has_score_events or (
+                previous_round_players_count > 0 and previous_round_guess_count >= previous_round_players_count
+            )
+            if not previous_round_reveal_resolved:
+                return api_error(request, code="next_round_invalid_phase", status=400)
+
             next_round_config = RoundConfig.objects.filter(
                 session=locked_session,
                 number=locked_session.current_round,