Alexis Sanchez fears he could miss up to two months with knee ligament damage suffered on Saturday.
The Manchester United forward was forced off seven minutes into the second half of the 3-2 win over Southampton after a collision with Jan Bednarek.
Chile’s national team physio, Pedro Onate, claimed Sanchez is likely to miss between six and eight weeks.
“We spoke to the player and he had scans on the injury (on Sunday),” Onate told El Mercurio.
“He will be available for the Copa America, but he will be unavailable to play for between six and eight weeks.
“The medial ligament strain is an annoying injury but not such a complex one.”
Sanchez’s absence represents a significant blow for Ole Gunnar Solskjaer, who could be without up to 10 stars for Wednesday’s Champions League date with Paris Saint-Germain.
Paul Pogba is missing through suspension, while Juan Mata, Antonio Valencia, Ander Herrera, Nemanja Matic, Jesse Lingard and Matteo Darmian are all injured. Phil Jones has been unwell, while Anthony Martial is unlikely to be risked.
Sanchez’s form has been troubling for United, with the striker having only scored twice for the club since last April.
Chile boss Reinaldo Rueda has expressed his concerns as well.
“For sure, it’s very worrying,” Rueda said. “These are situations that happen in football.
“We hope he overcomes this very quickly because he has all the quality, a track record, experience and quality to assert himself.
“I hope we can enjoy the Alexis we all knew again.” – MailOnline