Lukaku is yet to feature for the Red Devils in their on-going pre-season campaign, having been ruled out with injury and his manager believes the side are performing well without him.
When quizzed on the absence of Lukaku after a win over Antonio Conte’s Inter Milan on Saturday, Norwegian trainer Ole Gunnar Solskjaer said;
"I think we have done really well without Romelu, but we all know he is one of the top, top strikers in the world," he told a media conference.
"We played a different way, maybe, with Anthony [Martial], Marcus [Rashford] and Mason.
"As a coach you adapt to the players that are available. We're looking forward to the game against Tottenham [on Thursday] and let's see who is available for that game.
"If you're a player and you don't manage to train for a week, and he's missed three games now, I think he'll be concerned.
"He's working to get back on the pitch and we'll see how long that takes."
Following the arrival of Solskjaer, Lukaku has enjoyed limited first-team opportunities, playing second fiddle to Marcus Rashford and is said to be angling for a move to Italian Serie A giants Inter Milan, a destination he suggests could be a first-team regular.
And with the transfer window still in progress, a move for the bulky striker is still possible as Conte previously regarded him as an important prospect to fit his squad.