Everton were left counting the cost of another injury during the international break after Argentina defender Ramiro Funes Mori was carried off.
The centre-back was shown holding his left knee as he left the pitch after only 36 minutes of Argentina's 2-0 defeat by Bolivia on Tuesday evening.
The Toffees have already seen Seamus Coleman sidelined until next season with a horrific leg break suffered during the Republic of Ireland's draw with Wales last Friday.
Midfielder James McCarthy, meanwhile, did not even make it to kick-off in Dublin after aggravating a hamstring problem in the warm-up.
Funes Mori has made 26 appearances for Everton this season, but lost his place to Phil Jagielka for the last two Premier League matches against West Brom and Hull.
The injuries are particularly bad timing for boss Ronald Koeman, with a run of nine wins from 15 games drawing them level on 50 points with sixth-placed Arsenal.
Everton return to league action on Sunday in the Merseyside derby against Liverpool at Anfield.