Benjamin Sesko will be out of action for around a month with a knee injury he picked up against Tottenham, at a time when he needs to prove his value to Manchester United.
He joined from RB Leipzig for £74m in August but has been struggling for goals. And was hurt during the 2-2 draw on 8 November against Spurs. He came on as a substitute and missed a couple of chances before getting injured.
Ruben Amorim said afterwards he did not know if it was a serious problem, and club sources have played down fears the Slovenia forward suffered a major injury.
However, the 22-year-old was ruled out of Slovenia's World Cup qualifiers and it is now expected he will miss about four weeks, though the precise length of his absence is still to be determined.
Amorim is set to offer an update on the situation this week at a news conference before Monday's Premier League game with Everton at Old Trafford.
Meanwhile Paul Merson and Paul Scholes have blamed the United system for Sesko's struggles at the club. Sesko has scored two goals in 12 matches since he joined United.
Merson said: "He’s gone out and bought Sesko, he’s never going to score a goal because there is no one who is going to cross the ball in.
"He has two players behind now in Cunha and Mbeumo, who are cuffy - they are off the cuff. They are going to get the ball and they might beat three players and score, they might beat three and put the ball wide - you are never going to get someone outside to put the ball in the box.I feel sorry for the centre forward.
And Scholes agreed: "He’s 6ft 5in that centre forward and you think of United historically, wide players, players who get you off your seat, who cross the ball.
"They’ve signed a 6ft 5in centre forward, we used to have fullbacks who could cross a ball, Gary Neville, Denis Irwin (….) I can’t tell you how
Man Utd score a goal."
The good news for United is that Sesko should be back before Mbeumo and Amad Diallo head off for the Africa Cup of Nations, which begins in Morocco on 21 December. United have a home game against Bournemouth on 15 December.