diff --git a/weed/s3api/filer_multipart.go b/weed/s3api/filer_multipart.go
index 6a113f9e4..126a91589 100644
--- a/weed/s3api/filer_multipart.go
+++ b/weed/s3api/filer_multipart.go
@@ -30,6 +30,7 @@ import (
 
 	"github.com/seaweedfs/seaweedfs/weed/filer"
 	"github.com/seaweedfs/seaweedfs/weed/glog"
+	"github.com/seaweedfs/seaweedfs/weed/pb"
 	"github.com/seaweedfs/seaweedfs/weed/pb/filer_pb"
 )
 
@@ -553,9 +554,16 @@ func (s3a *S3ApiServer) completeMultipartUpload(r *http.Request, input *s3.Compl
 	uploadDirectory := s3a.genUploadsFolder(*input.Bucket) + "/" + *input.UploadId
 	entryName, dirName := s3a.getEntryNameAndDir(input)
 	var completionState *multipartCompletionState
-	finalizeCode := s3a.withObjectWriteLock(*input.Bucket, *input.Key, func() s3err.ErrorCode {
-		return s3a.checkConditionalHeaders(r, *input.Bucket, *input.Key)
-	}, func() s3err.ErrorCode {
+	// Non-versioned destination: the final write is a single CreateEntry, so route
+	// it (with the precondition) to the object's owner and skip the distributed
+	// lock. Assembly and the idempotency replay below are read-only and safe
+	// outside any lock. Versioned/suspended completions keep the lock path.
+	mpuCond, mpuCondOk := buildWriteCondition(r)
+	var nvOwner pb.ServerAddress
+	if vs, vErr := s3a.getVersioningState(*input.Bucket); vErr == nil && vs == "" && mpuCondOk {
+		nvOwner, _ = s3a.routedObjectOwner(*input.Bucket, *input.Key)
+	}
+	finalizeBody := func() s3err.ErrorCode {
 		var prepCode s3err.ErrorCode
 		completionState, output, prepCode = s3a.prepareMultipartCompletionState(r, input, uploadDirectory, entryName, dirName, completedPartNumbers, completedPartMap, maxPartNo)
 		if prepCode != s3err.ErrNone || output != nil {
@@ -739,7 +747,7 @@ func (s3a *S3ApiServer) completeMultipartUpload(r *http.Request, input *s3.Compl
 		}
 
 		// For non-versioned buckets, create main object file
-		if err := s3a.mkFile(dirName, entryName, completionState.finalParts, func(entry *filer_pb.Entry) {
+		nvModifier := func(entry *filer_pb.Entry) {
 			if entry.Extended == nil {
 				entry.Extended = make(map[string][]byte)
 			}
@@ -787,7 +795,14 @@ func (s3a *S3ApiServer) completeMultipartUpload(r *http.Request, input *s3.Compl
 			if completionState.entityWithTtl {
 				entry.Extended[s3_constants.SeaweedFSExpiresS3] = []byte("true")
 			}
-		}); err != nil {
+		}
+		if nvOwner != "" {
+			// Routed path: the owner evaluates the precondition and writes under
+			// its local lock, so the lock wrapper below is skipped.
+			if code := s3a.mkFileRouted(nvOwner, dirName, entryName, completionState.finalParts, mpuCond, nvModifier); code != s3err.ErrNone {
+				return code
+			}
+		} else if err := s3a.mkFile(dirName, entryName, completionState.finalParts, nvModifier); err != nil {
 			glog.Errorf("completeMultipartUpload %s/%s error: %v", dirName, entryName, err)
 			return s3err.ErrInternalError
 		}
@@ -802,7 +817,17 @@ func (s3a *S3ApiServer) completeMultipartUpload(r *http.Request, input *s3.Compl
 			ChecksumValue:      completionState.checksumValue,
 		}
 		return s3err.ErrNone
-	})
+	}
+	var finalizeCode s3err.ErrorCode
+	if nvOwner != "" {
+		// Routed non-versioned completion: no distributed lock, no gateway
+		// precondition here — the routed write carries the condition.
+		finalizeCode = finalizeBody()
+	} else {
+		finalizeCode = s3a.withObjectWriteLock(*input.Bucket, *input.Key, func() s3err.ErrorCode {
+			return s3a.checkConditionalHeaders(r, *input.Bucket, *input.Key)
+		}, finalizeBody)
+	}
 	if finalizeCode != s3err.ErrNone {
 		return nil, finalizeCode
 	}
diff --git a/weed/s3api/s3api_object_routed_write.go b/weed/s3api/s3api_object_routed_write.go
index f9e354f16..1273f7aab 100644
--- a/weed/s3api/s3api_object_routed_write.go
+++ b/weed/s3api/s3api_object_routed_write.go
@@ -5,7 +5,9 @@ import (
 	"fmt"
 	"net/http"
 	"strings"
+	"time"
 
+	"github.com/seaweedfs/seaweedfs/weed/glog"
 	"github.com/seaweedfs/seaweedfs/weed/pb"
 	"github.com/seaweedfs/seaweedfs/weed/pb/filer_pb"
 	"github.com/seaweedfs/seaweedfs/weed/s3api/s3_constants"
@@ -115,6 +117,53 @@ func singleStrongETag(v string) (string, bool) {
 	return strings.Trim(v, `"`), true
 }
 
+// mkFileRouted builds a file entry the way filer_pb.MkFile does, applies fn, and
+// routes the CreateEntry (with an optional precondition) to the given owner filer
+// so its local per-path lock serializes the write. Used by callers that build an
+// object via a modifier (e.g. multipart completion) but want the routed,
+// distributed-lock-free write path.
+func (s3a *S3ApiServer) mkFileRouted(owner pb.ServerAddress, dir, name string, chunks []*filer_pb.FileChunk, cond *filer_pb.WriteCondition, fn func(*filer_pb.Entry)) s3err.ErrorCode {
+	now := time.Now().Unix()
+	entry := &filer_pb.Entry{
+		Name:        name,
+		IsDirectory: false,
+		Attributes: &filer_pb.FuseAttributes{
+			Mtime:    now,
+			Crtime:   now,
+			FileMode: uint32(0770),
+			Uid:      filer_pb.OS_UID,
+			Gid:      filer_pb.OS_GID,
+		},
+		Chunks: chunks,
+	}
+	if fn != nil {
+		fn(entry)
+	}
+	resp, err := s3a.createEntryOnFiler(owner, &filer_pb.CreateEntryRequest{
+		Directory: dir,
+		Entry:     entry,
+		Condition: cond,
+	})
+	switch {
+	case err != nil:
+		glog.Errorf("mkFileRouted: %s/%s on %s: %v", dir, name, owner, err)
+		return s3err.ErrInternalError
+	case resp.ErrorCode == filer_pb.FilerError_PRECONDITION_FAILED:
+		return s3err.ErrPreconditionFailed
+	case resp.ErrorCode != filer_pb.FilerError_OK:
+		if code, ok := filerErrorCodeToS3Error(resp.ErrorCode); ok {
+			return code
+		}
+		glog.Errorf("mkFileRouted: %s/%s unexpected code %v", dir, name, resp.ErrorCode)
+		return s3err.ErrInternalError
+	case resp.Error != "":
+		glog.Errorf("mkFileRouted: %s/%s: %s", dir, name, resp.Error)
+		return s3err.ErrInternalError
+	default:
+		return s3err.ErrNone
+	}
+}
+
 // createEntryOnFiler sends a CreateEntry directly to the given owner filer so
 // its local per-path lock serializes the write. The raw response is returned so
 // the caller can distinguish PRECONDITION_FAILED from other outcomes.