Manchester United defender Lisandro Martinez is expected to be out for two to three months with a foot injury.
The 25-year-old Argentina international missed the end of last season after fracturing a metatarsal in April.
He returned to action at the start of this season but United say he will be sidelined again because of “an aggravation” to the injury.
The club said Martinez “experienced the setback in our Premier League game against Arsenal earlier this month”.
They added: “It has now been determined that he needs a period on the sidelines for recovery and rehabilitation.
“Assessment is ongoing to determine next steps.”
At a news conference on Friday, manager Erik ten Hag said: “It is very sad, for him and the team, because he was not 100% fit.
“I think it was a big difference, the Licha Martinez in the last games and the Licha Martinez we have seen in the last season.”