Mikel Merino will undergo surgery on a bone injury in his right foot, with Arsenal confirming he will be out for an "extended period".
The Spaniard sustained the injury towards the end of Arsenal's 3-2 loss to Manchester United last weekend and subsequently missed their matches against Kairat Almaty and Leeds United.
Following the latter, Mikel Arteta said Merino would see a specialist to determine a full prognosis.
And after undergoing those tests, Merino's injury will require surgery, though they are optimistic he will return before the end of the season.
Merino has made 33 appearances for Arsenal in all competitions this term, scoring six goals in all competitions, the most among midfielders at the club.
He has also provided three assists from 26 chances created, with only six players in the squad setting up more.
