The Belgian forward has been in top form for the Red Devils since signing for Jose Mourinho’s team from Everton back in July.
The 24-year-old has netted seven goals in his first nine Premier League games to help Manchester United up to second place in the table.
The striker has shown no signs of struggling to adapt to the rigours of life at Manchester United and looks as if he will be a key player for the Red Devils in the seasons to come.
Lukaku’s fine form is likely to make it difficult for Ibrahimovic to break back into the first team at Old Trafford.
However, the Swedish striker has been very impressed by what he has seen from the Belgium international in recent weeks.
Speaking to MUTV, Ibrahimovic said: “He’s doing fantastically well, but it’s no surprise.
“The only difference now is that he’s doing it at a big club, with all due respect for Everton and all the other clubs he played for. Now he’s doing it on the big scene where the pressure is totally different.
“I think when you’re playing for a top five club in the world, the pressure is different compared to other clubs, with all due respect to them.
“And now he’s doing it on the big scene, he’s showing what he’s good at – scoring goals. He’s a powerful machine.”
Manchester United are currently preparing for their crunch Premier League clash against Tottenham Hotspur at Old Trafford on Saturday afternoon.
The Red Devils head into the game looking to bounce back to winning ways after their shock 2-1 loss to Huddersfield last weekend.
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