Everton defender Ramiro Funes Mori is set to miss the rest of the season after suffering a serious knee injury playing for Argentina.
Funes Mori was stretchered off with a torn meniscus in the first half of Argentina's World Cup qualifier against Bolivia in La Paz earlier this week.
The centre-back is unlikely to return from the injury before the end of Everton's Premier League campaign.
"It has been confirmed that the defender suffered a torn meniscus in Argentina's 2-0 defeat to Bolivia on Tuesday evening," Everton said in a statement on Thursday.
"He will have a surgical opinion next week but the initial diagnosis suggests the 26-year-old is likely to be out of action for the rest of the campaign."
It is another blow for Everton manager Ronald Koeman ahead of Saturday's Merseyside derby against Liverpool.
Everton had already lost right-back Seamus Coleman for several months with a double fracture of his leg playing for the Republic of Ireland against Wales last week.
Republic and Everton midfielder James McCarthy aggravated a hamstring injury in the warm-up to that game and may not be fit to feature against Liverpool.
Everton are currently seventh in the Premier League, six points behind fourth placed Liverpool, as they battle to qualify for Europe.