Lukakau did not celebrate his last two goals for the Red Devils and MirrorSport claims that his issues with Ibrahimovic are behind it.
The Belgium international was signed from Everton last summer for £75million, to effectively replace Ibrahimovic as the club’s source of goals upfront.
But Lukaku feels Ibrahimovic has refused to accept his status as the club’s No 9, since returning from a serious knee injury that had kept him out since April.
Lukaku still starts the big games for United, but has complained that Ibrahimovic has tried to take over his central striking role when he has come on as a substitute, telling him to move out wide.
He is also not pleased that manager Jose Mourinho, have not spoken to the Swede about this behaviour.
Lukaku has managed four goals in 10 games since Ibrahimovic returned, compared to scoring 11 in his first 10 matches.