Arsenal defenders Nacho Monreal and Sokratis Papastathopoulos will both undergo late fitness tests before the Europa League clash with Sporting CP.
Spanish full-back Monreal has been absent for the last five games due to a hamstring problem, though Sead Kolasinac did return for the weekend draw against Liverpool.
An ankle problem has meanwhile prevented Greek defender Sokratis from playing since the 1-0 win in Lisbon two weeks ago - though he has not appeared in the Gunners' last five Premier League matches.
However, both players in training on Wednesday but it remains to be seen whether they will overcome their recent injury problems to start the game.