Arsenal left-back Kieran Tierney was forced off with a knee injury during the Gunners' 3-0 defeat to Liverpool in the Premier League on Saturday evening.
Mikel Arteta already had to make do with four first-team regulars for the visit of the champions, as Bukayo Saka, Emile Smith Rowe, David Luiz and Granit Xhaka were all ruled out of the game with various ailments.
Tierney was named in the starting lineup on Saturday, but a collision with James Milner left the Scottish defender clutching his knee on the Emirates turf just before half time, and he had to be replaced by Cedric Soares in yet another blow to Arteta's Arsenal.
After the game, the Arsenal manager confirmed that Tierney felt pain in his knee and is likely to spend a spell on the sidelines, but he was unable to give an immediate timeframe on the defender's return.
As a result, the former Celtic man is certainly expected to miss Thursday's Europa League quarter-final first leg with Slavia Prague, and Arteta also revealed that David Luiz may need to go under the knife for his injury, which could rule him out for the rest of the season.
Two goals from Diogo Jota either side of a Mohamed Salah strike saw Liverpool ease to victory after Tierney went off at the Emirates.