diff --git a/Assets/PerfectWorld/Prefab/UI/PlayerOptionPopup.prefab b/Assets/PerfectWorld/Prefab/UI/PlayerOptionPopup.prefab
index ba4ca439d2..61f908b24d 100644
--- a/Assets/PerfectWorld/Prefab/UI/PlayerOptionPopup.prefab
+++ b/Assets/PerfectWorld/Prefab/UI/PlayerOptionPopup.prefab
@@ -1208,7 +1208,7 @@ MonoBehaviour:
   m_OnCullStateChanged:
     m_PersistentCalls:
       m_Calls: []
-  m_text: Invite
+  m_text: "Th\xE1ch \u0111\u1EA5u\n"
   m_isRightToLeft: 0
   m_fontAsset: {fileID: 11400000, guid: 369c2e14814cc9a4b8e3ad4e37769134, type: 2}
   m_sharedMaterial: {fileID: 9092487103257209053, guid: 369c2e14814cc9a4b8e3ad4e37769134, type: 2}
diff --git a/Assets/PerfectWorld/Scripts/Managers/EC_HPWorkTrace.cs b/Assets/PerfectWorld/Scripts/Managers/EC_HPWorkTrace.cs
index 652d2799c3..fdd5b8c8f9 100644
--- a/Assets/PerfectWorld/Scripts/Managers/EC_HPWorkTrace.cs
+++ b/Assets/PerfectWorld/Scripts/Managers/EC_HPWorkTrace.cs
@@ -262,10 +262,14 @@ namespace BrewMonster
                     // 为了保证追踪到目标后能正常攻击，这里在必要时主动选中目标。
                     // Server select-target ack can arrive later than the trace touch moment, which would
                     // make this block forever. Ensure we select the traced target before attacking.
+                    // In duel: don't overwrite selection if player explicitly chose another target.
+                    bool duelPlayerChoseOther = m_pHost.IsInDuel() && m_pHost.GetDuelOpponentId() == m_iObjectId
+                        && m_pHost.m_idSelTarget != 0 && m_pHost.m_idSelTarget != m_iObjectId;
                     if (m_iObjectId != m_pHost.m_idSelTarget)
                     {
                         UnityGameSession.c2s_CmdSelectTarget(m_iObjectId);
-                        m_pHost.m_idSelTarget = m_iObjectId;
+                        if (!duelPlayerChoseOther)
+                            m_pHost.m_idSelTarget = m_iObjectId;
                     }
                     if (m_pHost.AttackableJudge(m_iObjectId, m_bForceAttack) == 1)
                     {
@@ -381,10 +385,14 @@ namespace BrewMonster
             {
                 // 同 NPC：追踪触碰可能早于服务器选中目标同步，需主动选中以避免攻击不触发。
                 // Same as NPC: trace touch can happen before server selection ack; proactively select.
+                // In duel: don't overwrite selection if player explicitly chose another target.
+                bool duelPlayerChoseOther = m_pHost.IsInDuel() && m_pHost.GetDuelOpponentId() == m_iObjectId
+                    && m_pHost.m_idSelTarget != 0 && m_pHost.m_idSelTarget != m_iObjectId;
                 if (m_iObjectId != m_pHost.m_idSelTarget)
                 {
                     UnityGameSession.c2s_CmdSelectTarget(m_iObjectId);
-                    m_pHost.m_idSelTarget = m_iObjectId;
+                    if (!duelPlayerChoseOther)
+                        m_pHost.m_idSelTarget = m_iObjectId;
                 }
                 // Duel: always send PVP/force mask when target is duel opponent so server accepts the attack
                 bool bUseForceAttack = m_bForceAttack || (m_pHost.IsInDuel() && m_iObjectId == m_pHost.GetDuelOpponentId());
diff --git a/Assets/PerfectWorld/Scripts/Managers/EC_HostInputFilter.cs b/Assets/PerfectWorld/Scripts/Managers/EC_HostInputFilter.cs
index 3177d02b80..89884d340e 100644
--- a/Assets/PerfectWorld/Scripts/Managers/EC_HostInputFilter.cs
+++ b/Assets/PerfectWorld/Scripts/Managers/EC_HostInputFilter.cs
@@ -407,8 +407,10 @@ namespace BrewMonster
                 // Trace a object / Trace a object
                 if (iTraceReason == CECHPWorkTrace.Trace_reason.TRACE_ATTACK)
                 {
-                    // So CanDo(CANDO_MELEE) passes: it requires m_idSelTarget set to the attack target
-                    m_idSelTarget = idTraceTarget;
+                    // So CanDo(CANDO_MELEE) passes and target HUD updates (e.g. duel opponent)
+                    SetSelectedTarget(idTraceTarget);
+                    // Sync selected target to server so attack is not rejected (wrong target / too far)
+                    UnityGameSession.c2s_CmdSelectTarget(idTraceTarget);
                     if (!CanDo(ActionCanDo.CANDO_MELEE))
                         return;
                     // When attacking duel opponent, send force/PVP so server accepts (origin: duel = attack but not kill)
@@ -448,6 +450,8 @@ namespace BrewMonster
             if (idSelTarget != 0 && m_idSelTarget != idSelTarget)
             {
                 m_idUCSelTarget = idSelTarget;
+                // Update local selection and HUD first so first click changes target (e.g. in duel); then sync to server
+                SetSelectedTarget(m_idUCSelTarget);
                 SelectTarget(m_idUCSelTarget);
             }
         }
diff --git a/Assets/PerfectWorld/Scripts/Managers/EC_ManPlayer.cs b/Assets/PerfectWorld/Scripts/Managers/EC_ManPlayer.cs
index 9211f1736a..8c93446808 100644
--- a/Assets/PerfectWorld/Scripts/Managers/EC_ManPlayer.cs
+++ b/Assets/PerfectWorld/Scripts/Managers/EC_ManPlayer.cs
@@ -38,13 +38,12 @@ namespace PerfectWorld.Scripts.Managers
                     if ((int)Msg.dwMsg == EC_MsgDef.MSG_PM_DUELOPT && Convert.ToInt32(Msg.dwParam2) == CommandID.DUEL_RECV_REQUEST && Msg.dwParam1 is byte[] pDataBuf && pDataBuf.Length >= 4)
                     {
                         int inviterId = BitConverter.ToInt32(pDataBuf, 0);
-                        var gameUI = EC_Game.GetGameRun()?.GetUIManager()?.GetInGameUIMan();
-                        if (gameUI != null)
-                        {
-                            var dlg = gameUI.GetDialog("DlgDuelInvite");
-                            var showMethod = dlg?.GetType().GetMethod("ShowForDuelInvite", System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Instance, null, new[] { typeof(int) }, null);
-                            showMethod?.Invoke(dlg, new object[] { inviterId });
-                        }
+                        CECUIManager.Instance?.ShowMessageBox(
+                            title: "",
+                            message: "You have received a duel request. Do you accept?",
+                            messageBoxType: MessageBoxType.BothYesNoButton,
+                            onClickedYes: () => UnityGameSession.c2s_CmdDuelReply(true, inviterId),
+                            onClickedNo: () => UnityGameSession.c2s_CmdDuelReply(false, inviterId));
                     }
                     CECGameRun.Instance.GetHostPlayer().ProcessMessage(Msg);
                 }
diff --git a/Assets/PerfectWorld/Scripts/Network/CSNetwork/C2SCommand/C2SCommandFactory.cs b/Assets/PerfectWorld/Scripts/Network/CSNetwork/C2SCommand/C2SCommandFactory.cs
index f0440f4937..4ed0b279d7 100644
--- a/Assets/PerfectWorld/Scripts/Network/CSNetwork/C2SCommand/C2SCommandFactory.cs
+++ b/Assets/PerfectWorld/Scripts/Network/CSNetwork/C2SCommand/C2SCommandFactory.cs
@@ -824,10 +824,14 @@ namespace CSNetwork.C2SCommand
             return SerializeCommand(CommandID.DUEL_REQUEST, new cmd_team_new_member { idMember = idTarget });
         }
 
-        /// <summary>C2S: accept (true) or reject (false) duel from inviter.</summary>
+        /// <summary>C2S: accept (true) or reject (false) duel from inviter. Origin: [cmd][who:4][param:4] — who=inviter id, param=0 accept / non-zero reject.</summary>
         public static Octets CreateDuelReplyCommand(bool accept, int idInviter)
         {
-            return SerializeCommand(CommandID.DUEL_REPLY, new cmd_duel_reply { accept = accept ? 1 : 0, idInviter = idInviter });
+            var octets = new Octets();
+            WriteBasicValue(octets, (ushort)CommandID.DUEL_REPLY);
+            WriteBasicValue(octets, idInviter);  // who
+            WriteBasicValue(octets, accept ? 0 : 1);  // param: 0 = accept, non-zero = reject reason
+            return octets;
         }
 
         public static Octets CreateTeamKickMemberCommand(int idMember)
diff --git a/Assets/PerfectWorld/Scripts/Network/CSNetwork/GPDataType.cs b/Assets/PerfectWorld/Scripts/Network/CSNetwork/GPDataType.cs
index f7ebb1055e..d661617ad6 100644
--- a/Assets/PerfectWorld/Scripts/Network/CSNetwork/GPDataType.cs
+++ b/Assets/PerfectWorld/Scripts/Network/CSNetwork/GPDataType.cs
@@ -2188,12 +2188,12 @@ namespace CSNetwork.GPDataType
         public int idMember;
     }
 
-    /// <summary>C2S duel reply: accept (1) / reject (0) and inviter character id.</summary>
+    /// <summary>C2S duel reply (origin: who = inviter id, param = 0 accept / non-zero reject reason).</summary>
     [StructLayout(LayoutKind.Sequential, Pack = 1)]
     public struct cmd_duel_reply
     {
-        public int accept;   // 1 = accept, 0 = reject
-        public int idInviter;
+        public int who;   // inviter character id (who sent the duel request)
+        public int param; // 0 = accept (同意), non-zero = reject reason (拒绝原因)
     }
 
     [StructLayout(LayoutKind.Sequential, Pack = 1)]
diff --git a/Assets/Scripts/CECHostPlayer.cs b/Assets/Scripts/CECHostPlayer.cs
index 325f77becd..3206e612ad 100644
--- a/Assets/Scripts/CECHostPlayer.cs
+++ b/Assets/Scripts/CECHostPlayer.cs
@@ -1106,6 +1106,9 @@ namespace BrewMonster
             {
                 var data = (byte[])Msg.dwParam1;
                 cmd_select_target pCmd = GPDataTypeHelper.FromBytes<cmd_select_target>(data);
+                // In duel: don't let server force selection back to duel opponent when player chose another target
+                if (IsInDuel() && pCmd.idTarget == m_pvp.idDuelOpp && m_idSelTarget != 0 && m_idSelTarget != m_pvp.idDuelOpp)
+                    return;
                 m_idSelTarget = pCmd.idTarget;
                 m_idUCSelTarget = 0;
             }
@@ -1895,7 +1898,6 @@ namespace BrewMonster
 
         public bool SelectTarget(int idTarget)
         {
-            //BMLogger.LogError("HoangDev: HostPlayer SelectTarget");
             bool bRet = false;
             bool canDo = CanDo(ActionCanDo.CANDO_CHANGESELECT);
             bool canselect = CanSelectTarget(idTarget);
@@ -2374,7 +2376,23 @@ namespace BrewMonster
         }
         public void SetSelectedTarget(int id)
         {
+            if (m_idSelTarget != id)
+                EventBus.Publish(new CECHostPlayer.TargetHUDClearEvent());
             m_idSelTarget = id;
+            // In duel, when player selects a different target, cancel trace work so it doesn't overwrite selection on touch
+            if (IsInDuel() && id != 0 && id != m_pvp.idDuelOpp)
+                m_pWorkMan?.FinishRunningWork(CECHPWork.Host_work_ID.WORK_TRACEOBJECT);
+            // When selecting another player, publish NPCINFO so target HUD shows (server doesn't resend base info on select)
+            if (id != 0 && id != GetCharacterID() && GPDataTypeHelper.ISPLAYERID(id))
+            {
+                var elsePlayer = EC_ManMessageMono.Instance?.GetECManPlayer?.GetPlayer(id) as EC_ElsePlayer;
+                if (elsePlayer != null && elsePlayer.m_bBaseInfoReady)
+                {
+                    string name = elsePlayer.GetName();
+                    if (!string.IsNullOrEmpty(name))
+                        EventBus.Publish(new CECHostPlayer.NPCINFO(name, 100, 100, id));
+                }
+            }
         }
 
         public new int GetSelectedTarget()
diff --git a/Assets/Scripts/CECUIManager.cs b/Assets/Scripts/CECUIManager.cs
index 9e9715d792..a9c6906992 100644
--- a/Assets/Scripts/CECUIManager.cs
+++ b/Assets/Scripts/CECUIManager.cs
@@ -112,6 +112,9 @@ public class CECUIManager : MonoSingleton<CECUIManager>
 
     private void ShowUINPC(CECHostPlayer.NPCINFO obj)
     {
+        var host = EC_Game.GetGameRun()?.GetHostPlayer();
+        if (host != null && host.GetSelectedTarget() != obj.IDNPC)
+            return;
         npsUI.gameObject.SetActive(true);
         string hpText = obj.MaxHealth > 0 ? $"{obj.CurrentHealth}/{obj.MaxHealth}" : "-/-";
         npsUI.SetText(hpText, obj.Name ?? "", "");