Manchester United centre-back Lisandro Martinez will miss the rest of the season after fracturing a metatarsal bone in his foot.
The 25-year-old sustained the injury in United's 2-2 Europa League quarter-final against Sevilla on Thursday.
Erik ten Hag's side were reduced to 10 men when Martinez was helped off in the 86th minute with United leading 2-1.
Martinez's centre-back partner Raphael Varane also sustained an injury and is expected to be out for a few weeks.
"Everyone at Manchester United sends Lisandro and Rapha our best wishes for a speedy recovery," the club said.
Martinez, a World Cup winner with Argentina, was helped off the pitch at Old Trafford by Sevilla's Gonzalo Montiel and Marcos Acuna, his international team-mates.
He was then placed on a stretcher and carried away for treatment.
Martinez joined United from Ajax last July in a deal worth up to £57m and has played in 27 of United's Premier League matches this season.
France defender Varane, who joined the club from Real Madrid in August 2021, has made 21 league appearances this season.
He picked up an injury just before half-time and was replaced by Harry Maguire at the interval.
United are fourth in the Premier League with nine games remaining and the club are still in the FA Cup as well as the Europa League.
Speaking before United's league game against Nottingham Forest on Sunday, manager Ten Hag said: "We have a lot of decent centre-halves. We have proved in the past and in this season that we have four or five very good centre-halves who can do the job."
Centre-backs Maguire and Victor Lindelof are the likely options to fill in for Martinez and Varane.
Left-back Luke Shaw, who has played at centre-back at times this season, has missed the past two games with a hamstring injury but Ten Hag said the England international could return on Sunday.
The club are also without their top scorer Marcus Rashford, who sustained a muscle injury in United's win over Everton on Saturday.
After the Forest game, United travel to Sevilla on Thursday for the return leg of their Europa League quarter-final before facing Brighton three days later in an FA Cup semi-final, for which Maguire is suspended.
Source: BBC