Manchester United fear Lisandro Martínez could be set for months on the sidelines with the knee injury he suffered during the defeat to Crystal Palace, a source has told ESPN.

Martínez was stretched off during the second half of the 2-0 loss at Old Trafford on Sunday. The defender underwent tests on Monday.

He's set to have further scans this week, but there is concern Martínez has suffered a serious knee ligament injury which could rule him out for more than six months.

ESPN have approached United for comment.

Speaking at his post-match news conference on Sunday, United head coach Ruben Amorim said: "Licha is really important for us, not just as a football player, but as a character, especially in this hard moment.

"Now it's time to help Licha [Martinez]. I think it's a bad situation. Let's wait to assess things with the doctor but I think it's a serious situation."

It would represent another significant injury set-back for Martínez since arriving from Ajax in 2022. He suffered a fractured metatarsal in April 2023 which ended his first season at Old Trafford.

After making his comeback at the start of the 2023-24 campaign, a recurrence of the problem kept the 27-year-old sidelined between September 2023 and January 2024.

Following another comeback, knee and calf problems meant he was only able to start the final two games of last season -- the second being the FA Cup victory over Manchester City at Wembley.

Martinez's absence could mean new signing Ayden Heaven is fast-tracked following his January move from Arsenal. The 18-year-old is considered a first-team signing and, like Martinez, is predominantly a left-sided centre-back.