Manchester United defender Lisandro Martinez is facing at least eight weeks out with ligament damage in his right knee.
The Argentina defender was forced off in the 71st minute of United's 3-0 win over West Ham at Old Trafford on Sunday, just his fourth appearance following four months out following a foot issue.
Martinez was surrounded by concerned United team-mates in the second half of the Premier League game after going down clutching his knee having been landed on awkwardly by West Ham full-back Vladimir Coufal.
A statement from Manchester United read: "Lisandro Martinez has sustained an injury to the medial collateral ligament in his knee and is expected to be out of action for at least eight weeks.
"The Argentine defender left the field in the 71st minute of our 3-0 win over West Ham United at Old Trafford on Sunday.
"We all wish Licha a speedy recovery and look forward to seeing him back on the pitch later in the season."
Meanwhile, Alejandro Garnacho says improving United must maintain momentum as they look to claw themselves into the Champions League qualification spots.
A promising first season under Erik ten Hag has been followed by a challenging second campaign filled with more downs than ups, thanks in no small part to a swathe of injuries.
The drop off means United have no European football after Christmas but there has been a recent upturn in fortunes and they usurped West Ham in sixth after Garnacho's brace.
The Red Devils remain six points behind Tottenham in fifth - a position that may be enough for Champions League qualification - and a further two behind fourth-placed Aston Villa, where Ten Hag's team head on Sunday.
"I am always trying to help the team by either scoring or assisting," Garnacho said after his second-half double at the weekend.
"I don't care if Rasmus (Hojlund) or (Marcus) Rashford scores, I think we have to win and we have to be in the top six again.
"Hopefully, you know, (I could get) 10, 12 goals (by the end of the season).
"Now we go over West Ham into the top six but of course we want to be in the Champions League the next year, so we have to keep this momentum and try to win the next game."
United have won four of their five matches in all competitions since the turn of the year, drawing the other, with Hojlund scoring in each of his last four matches.
The summer signing celebrated his 21st birthday by opening the scoring on Sunday, continuing a fine run started when breaking his Premier League duck in the 3-2 St Stephen's Day turnaround against Villa.
"I am very happy for Rasmus and also because it is his birthday," Garnacho told MUTV.
"He had a difficult start but now he has scored (in) four games in a row. I am very happy for him and all of the team."
Hojlund's strike was complemented by Garnacho's brace, with his first goal celebrated by sitting on the advertising hoardings alongside fellow grinning young guns Hojlund and Kobbie Mainoo.
The latter scored a fantastic stoppage-time winner to secure Thursday's 4-3 victory at Wolves and Garnacho is full of praise for his 18-year-old team-mate and fellow 2022 FA Youth Cup winner.
"It is a dream for me and for Kobbie," the Argentina international said.
"Kobbie is a future star, for me, and also it is a good feeling because we played in the Under-18s and the Under-21s, we grew up together and I am very happy.
"If you have to play, you play, it doesn't matter if you are 18. I am happy for me and happy for the team."
While United turn their attention to Villa Park, the Hammers have to refocus on next Sunday's visit of high-flying Arsenal.
West Ham captain Kurt Zouma said after his side's Old Trafford defeat: "Everyone is disappointed, which is good because you don't want to lose games.
"We want to improve - we've got more time to prepare for a big game against Arsenal next week.
"Hopefully we're going to be ready for it and make sure we get the three points at home."
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