The Belgium international became Manchester United’s second most-expensive signing of all-time when the 24-year-old completed a move to Old Trafford from Premier League rivals Everton.
Lukaku was initially linked with a return to Premier League champions Chelsea before Lukaku opted to complete a switch to Manchester United to improve Jose Mourinho’s attacking options.
The powerful forward has already scored six times in six games in the Premier League to cast off doubts about his ability to perform at a top team in Europe.
The Belgian striker has carried his brilliant form in the Champions League after scoring three goals in victories over Basel and CSKA Moscow this month.
Former Manchester United captain Lukaku has been impressed with Jose Mourinho’s marquee summer signing following the striker’s return of 10 goals in all competitions this season.
“He’s a good player, a good age, he knows the Premier League,” Keane told ITV Sport on Wednesday night.
“He was a bargain at £75m. He’s got off to a good start, and seems like a decent character.”
Lukaku scored 25 times in 37 games in the Premier League last season to attract interest from Chelsea and Manchester United in the summer transfer window.
The Red Devils signed Benfica defender Victor Lindelof and Chelsea midfielder Nemanja Matic to improve their squad for a title tilt.
Manchester United will host Crystal Palace in the Premier League this weekend.
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