Granit Xhaka is out injured for Arsenal but Shkodran Mustafi is in contention to face Manchester United after resuming full training.
The midfielder is sidelined with an ankle injury sustained in the 2-0 loss at north London rivals Tottenham last Sunday, having been withdrawn just after the hour mark.
Mustafi has not played since the 3-0 away loss at Crystal Palace, missing three Premier League games and the FA Cup semi-final victory over Manchester City with a thigh injury.
In Mustafi's absence, Arsenal have moved to a three-man defence with success until defeat at Tottenham in the final north London derby at White Hart Lane and face a United team unbeaten since October this weekend.
"Granit Xhaka is still out from the kick he got from the game and Shkodran Mustafi is back in normal training," Wenger told reporters on Thursday morning.
"David Ospina is back and Lucas Perez is back in training but he will miss the next two days as he got a kick in training [on Wednesday]."
Arsenal face a heavily depleted United side on Sunday, with Jose Mourinho facing up to eight first-team players - including six defenders - potentially sidelined for the Emirates Stadium trip.
