The Belgian started life at Old Trafford with a bang with 11 goals in his first 11 games but has struggled since not finding the net since September.
But Roberto Martinez, his manager at former club Everton and now with national side Belgium, has come to the £75million man's defence insisting he will bounce back if he continues doing what he's doing.
"I've got a big advantage with Romelu because I've worked with him for four years," he said. "I know Romelu inside out. I think he just relishes the challenge. He's been enjoying a really good start to the season and now is a period he is ready to cope with.
"I have no worries whatsoever. All he needs to do in his career is to carry on being himself in a club with the expectations and the demand of Manchester United.
"For me nothing has changed in Romelu's mind. He is confident, he has an incredible belief in what he can bring.
"All I want is that he carries on seeing himself in that manner when he scores and when he doesn't, which is going to be highlighted in a club like Manchester United."
Lukaku's teammate Marouane Fellaini is working his way back to fitness and has been given added time off from international duty to get himself back to 100%.
"He needs a proper 10 days work with no game in order for him to be fully fit," he added. "Medically it is the right choice to allow Marouane to get fit. If it had been a competitive game I think we would have called him up because maybe for the second game he could have been on the pitch.
"This is a period where we can afford not to risk him until he is 100 per cent."
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