Ralf Rangnick is yet to settle on a perfect Manchester United XI.
And it seems academy graduate Mason Greenwood has done little to convince him he's deserving of a regular spot in his first team, according to reports.
Rangnick is keen to improve his United side's intensity. He wants the Red Devils to mimic other successful clubs in world football, who battle for every ball and are energetic in all aspects of the game.
When Rangnick took the reins from Ole Gunnar Solskjaer at United there were question marks over Cristiano Ronaldo's future.
The Portugal international is 36 now and this appeared to be a problem as Rangnick has previously made it clear he favours younger players.
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Greenwood, on the other hand, was tipped to play a starring role in the German's Man United side.
But so far it is Ronaldo who is clocking up the minutes while Greenwood is starting to find football harder to come by.
According to a report in The Guardian, Rangnick sees Greenwood as expendable. And he wants him to develop physically if he is to become an important player for him going forward.
Rangnick recently hooked Greenwood an hour into Man United's 1-0 defeat by Wolves, later telling the press: "His effort and performance was not outstanding but he was one of the better players today."
Rangnick has a balancing act on his hands at Old Trafford where he has a hugely inflated squad and a number of players who want to leave in the January transfer window.
According to reports, there are as many as 17 players who are jaded at United and looking at the exit.
Greenwood is not one of these players, and Rangnick would no doubt rather keep hold of the forward.
But unless the duo can come to some sort of compromise, which may require Greenwood knuckling down and improving his game to Rangnick's liking, the interim United boss may have a brand new problem on his hands.