diff --git a/backend/open_webui/main.py b/backend/open_webui/main.py
index 5136eb759..6b2df1b45 100644
--- a/backend/open_webui/main.py
+++ b/backend/open_webui/main.py
@@ -1705,8 +1705,10 @@ async def chat_completion(
                         default_models[0].strip() if default_models[0] else None
                     )
 
-                    if fallback_model_id:
-                        request.base_model_id = fallback_model_id
+                    if fallback_model_id and fallback_model_id in request.app.state.MODELS:
+                        # Update model and form_data so routing uses the fallback model's type
+                        model = request.app.state.MODELS[fallback_model_id]
+                        form_data["model"] = fallback_model_id
                     else:
                         raise Exception("Model not found")
                 else:
diff --git a/src/lib/components/chat/Chat.svelte b/src/lib/components/chat/Chat.svelte
index deae018fa..526147ed4 100644
--- a/src/lib/components/chat/Chat.svelte
+++ b/src/lib/components/chat/Chat.svelte
@@ -1031,12 +1031,13 @@
 		if (selectedModels.length === 0 || (selectedModels.length === 1 && selectedModels[0] === '')) {
 			if (availableModels.length > 0) {
 				if (defaultModels && defaultModels.length > 0) {
-					// Set from default models
 					selectedModels = defaultModels.filter((modelId) => availableModels.includes(modelId));
 				}
 
-				// Set to first available model
-				selectedModels = [availableModels?.at(0) ?? ''];
+				if (selectedModels.length === 0 || (selectedModels.length === 1 && selectedModels[0] === '')) {
+					// Only fall back to first available model if default models didn't resolve
+					selectedModels = [availableModels?.at(0) ?? ''];
+				}
 			} else {
 				selectedModels = [''];
 			}