Manchester United manager Jose Mourinho admitted he is concerned by Romelu Lukaku's goal drought after another blank against Juventus in the Champions League.

Lukaku and United were toothless as they were outclassed 1-0 by Juve at Old Trafford on Tuesday – the Belgian striker's scoreless streak for the club extending to eight matches.

The 25-year-old has scored four goals this season – all in the Premier League – though he has not found the back of the net since September 15 against Watford.

"Yeah," Mourinho replied when asked if he was concerned by Lukaku's impotence. "No critics at all, a complete understanding the player is a fantastic professional that wants to give everything for the team but I have to agree his moment is not sweet.

"Not just with the goals that he is not scoring but also in his confidence, in his movement, in his touch, he is not linking the game well with the team. But he's our striker and a good striker and a striker we believe in.

"Could I play [Marcus] Rashford there? But then I don't have a winger because in this moment we are in this difficult situation.

"He [Lukaku] is a hard-working guy, is a good professional, but one day the goal will arrive and the confidence will be back."