The Belgium global was as soon as once more at the scoresheet for United of their four-1 win over CSKA Moscow final night time.
Lukaku grabbed two first-part objectives to place Jose Mourinho’s aspect within the ascendency both sides of Anthony Martial’s spot kick with Henrikh Mkhitaryan including a fourth in the second one part.
Lukaku has now scored 10 objectives in simply 9 video games since his summer season transfer from Everton.
And United legend Keane believes the 24-year-outdated is proving to be a scouse borrow at £75million, but needs to peer Lukaku doing it towards United’s large opponents.
“He was a bargain at £75million, it was obvious he was going to score goals,” Keane stated on ITV.
“He has executed nice to this point, but the massive take a look at for them remains to be to come back for him.
“Man United have performed no one yet and despite the fact that you’ll be able to best beat what’s installed entrance of you, the larger checks will come.
“The most sensible United scorers have scored objectives that in point of fact topic down the years and he has to ship within the large video games.
“It’s to attain when your staff are 1-zero or 2-zero up, but you want to do it within the crunch video games.”
Lukaku can have a probability to extend his objective tally this weekend when United face Crystal Palace.