diff --git a/battle_srv/models/room.go b/battle_srv/models/room.go
index de158fa..ea71837 100644
--- a/battle_srv/models/room.go
+++ b/battle_srv/models/room.go
@@ -473,7 +473,7 @@ func (pR *Room) StartBattle() {
 						f := tmp.(*pb.InputFrameDownsync)
 						if pR.inputFrameIdDebuggable(candidateToSendInputFrameId) {
 							debugSendingInputFrameId = candidateToSendInputFrameId
-							Logger.Info("inputFrame lifecycle#3[sending]:", zap.Any("roomId", pR.Id), zap.Any("playerId", playerId), zap.Any("playerAckingInputFrameId", player.AckingInputFrameId), zap.Any("inputFrameId", candidateToSendInputFrameId), zap.Any("inputFrameId-doublecheck", f.InputFrameId), zap.Any("AllPlayerInputsBuffer", pR.AllPlayerInputsBufferString(false)), zap.Any("ConfirmedList", f.ConfirmedList))
+							Logger.Debug("inputFrame lifecycle#3[sending]:", zap.Any("roomId", pR.Id), zap.Any("playerId", playerId), zap.Any("playerAckingInputFrameId", player.AckingInputFrameId), zap.Any("inputFrameId", candidateToSendInputFrameId), zap.Any("inputFrameId-doublecheck", f.InputFrameId), zap.Any("AllPlayerInputsBuffer", pR.AllPlayerInputsBufferString(false)), zap.Any("ConfirmedList", f.ConfirmedList))
 						}
 						toSendInputFrames = append(toSendInputFrames, f)
 						candidateToSendInputFrameId++
@@ -511,7 +511,7 @@ func (pR *Room) StartBattle() {
 				f := pR.AllPlayerInputsBuffer.Pop().(*pb.InputFrameDownsync)
 				if pR.inputFrameIdDebuggable(f.InputFrameId) {
 					// Popping of an "inputFrame" would be AFTER its being all being confirmed, because it requires the "inputFrame" to be all acked
-					Logger.Info("inputFrame lifecycle#5[popped]:", zap.Any("roomId", pR.Id), zap.Any("inputFrameId", f.InputFrameId), zap.Any("AllPlayerInputsBuffer", pR.AllPlayerInputsBufferString(false)))
+					Logger.Debug("inputFrame lifecycle#5[popped]:", zap.Any("roomId", pR.Id), zap.Any("inputFrameId", f.InputFrameId), zap.Any("AllPlayerInputsBuffer", pR.AllPlayerInputsBufferString(false)))
 				}
 			}
 
@@ -579,15 +579,14 @@ func (pR *Room) OnBattleCmdReceived(pReq *pb.WsReq) {
 		inputFrameDownsync := tmp2.(*pb.InputFrameDownsync)
 		oldConfirmedList := atomic.LoadUint64(&(inputFrameDownsync.ConfirmedList))
 		if (oldConfirmedList & joinMask) > 0 {
-			Logger.Warn(fmt.Sprintf("Cmd already confirmed but getting set attempt, omitting this upsync cmd: roomId=%v, playerId=%v, clientInputFrameId=%v, AllPlayerInputsBuffer=%v", pR.Id, playerId, clientInputFrameId, pR.AllPlayerInputsBufferString(false)))
+			Logger.Debug(fmt.Sprintf("Cmd already confirmed but getting set attempt, omitting this upsync cmd: roomId=%v, playerId=%v, clientInputFrameId=%v, AllPlayerInputsBuffer=%v", pR.Id, playerId, clientInputFrameId, pR.AllPlayerInputsBufferString(false)))
 			return
 		}
 
 		// In Golang 1.12, there's no "compare-and-swap primitive" on a custom struct (or it's pointer, unless it's an unsafe pointer https://pkg.go.dev/sync/atomic@go1.12#CompareAndSwapPointer). Although CAS on custom struct is possible in Golang 1.19 https://pkg.go.dev/sync/atomic@go1.19.1#Value.CompareAndSwap, using a single word is still faster whenever possible.
-		if swapped := atomic.CompareAndSwapUint64(&inputFrameDownsync.InputList[indiceInJoinIndexBooleanArr], uint64(0), encodedInput); !swapped {
-			Logger.Warn(fmt.Sprintf("Failed input CAS: roomId=%v, playerId=%v, clientInputFrameId=%v", pR.Id, playerId, clientInputFrameId))
-			return
-		}
+
+        // [WARNING] No need to use CAS for updating "inputFrameDownsync.InputList[indiceInJoinIndexBooleanArr]", the upsync from frontend takes top priority.
+        atomic.StoreUint64(&inputFrameDownsync.InputList[indiceInJoinIndexBooleanArr], encodedInput);
 
 		newConfirmedList := (oldConfirmedList | joinMask)
 		if swapped := atomic.CompareAndSwapUint64(&(inputFrameDownsync.ConfirmedList), oldConfirmedList, newConfirmedList); !swapped {
diff --git a/frontend/assets/scenes/login.fire b/frontend/assets/scenes/login.fire
index 6324f99..cee1e6c 100644
--- a/frontend/assets/scenes/login.fire
+++ b/frontend/assets/scenes/login.fire
@@ -440,7 +440,7 @@
       "array": [
         0,
         0,
-        209.57814771583418,
+        209.63606633899616,
         0,
         0,
         0,
diff --git a/frontend/assets/scripts/Map.js b/frontend/assets/scripts/Map.js
index 739b185..d719ab1 100644
--- a/frontend/assets/scripts/Map.js
+++ b/frontend/assets/scripts/Map.js
@@ -947,6 +947,7 @@ cc.Class({
       rdf.id > self.lastAllConfirmedRenderFrameId
     ) {
       self.lastAllConfirmedRenderFrameId = rdf.id; 
+      self.chaserRenderFrameId = rdf.id; // it must be true that "chaserRenderFrameId >= lastAllConfirmedRenderFrameId"  
     }
     self._dumpToRenderCache(rdf); 
     return rdf;
@@ -978,7 +979,7 @@ cc.Class({
   },
 
   rollbackAndChase(renderFrameIdSt, renderFrameIdEd, collisionSys, collisionSysMap) {
-    if (renderFrameSt >= renderFrameIdEd) {
+    if (renderFrameIdSt >= renderFrameIdEd) {
       return;
     }
 
diff --git a/frontend/assets/scripts/WsSessionMgr.js b/frontend/assets/scripts/WsSessionMgr.js
index da2abec..38bd561 100644
--- a/frontend/assets/scripts/WsSessionMgr.js
+++ b/frontend/assets/scripts/WsSessionMgr.js
@@ -179,7 +179,7 @@ window.initPersistentSessionClient = function(onopenCb, expectedRoomId) {
           break;
         case window.DOWNSYNC_MSG_ACT_FORCED_RESYNC:
           if (window.handleInputFrameDownsyncBatch && window.handleRoomDownsyncFrame) {
-            console.warn("Got forced resync:", resp.toString(), " @localRenderFrameId=", mapIns.renderFrameId, ", @localRecentInputCache=", mapIns._stringifyRecentInputCache(false));
+            console.warn("Got forced resync:", JSON.stringify(resp), " @localRenderFrameId=", mapIns.renderFrameId, ", @localRecentInputCache=", mapIns._stringifyRecentInputCache(false));
             // The following order of execution is important, because "handleInputFrameDownsyncBatch" is only available when state is IN_BATTLE 
             window.handleRoomDownsyncFrame(resp.rdf);
             window.handleInputFrameDownsyncBatch(resp.inputFrameDownsyncBatch);