Ghanaian midfielder Thomas Partey will miss Arsenal's Europa League round of 32 first leg tie against Benfica on Thursday, Mikel Arteta has confirmed.
The 27-year-old has been plagued by injuries since his joining the Gunners from Atletico Madrid last year.
Partey sustained an injury in Arsenal's 1-0 defeat to Aston Villa in the Premier League and has been on the sidelines.
"Thomas didn't travel. He's not there yet, he's still training individually," Arteta said at his pre-match press conference.
"Kieran has had one session with us and is part of the squad."
"Although it is still not sure, if there is a player who has a greater chance of playing that match, it is Kieran."
"In the next few days I can surely complete some parts of the training with the team. But I don't know how it will evolve until the date approaches," added Arteta.
"Unfortunately, Thomas doesn't seem like he can recover in time.
Partey has made 16 appearances and scored one goal for Arsenal so far this season.