Arsenal midfielder Aaron Ramsey has been ruled out of the club's crucial Champions League clash against Schalke on Tuesday with a groin strain, while Theo Walcott is struggling with an illness.
Ramsey, 21, was forced to come off early with the injury during the second half of the 2-1 defeat at Manchester United on Saturday and will be replaced by Johan Djourou for the trip to Germany.
Gunners boss Arsene Wenger has confirmed that Walcott, 23, was sick on Sunday night but will travel with the team.
Despite talk of returns to fitness in time for Tuesday for Alex Oxlade-Chamberlain and Kieran Gibbs, nether player has won their battle.
The only other change to the squad from Saturday's game at Old Trafford sees goalkeeper James Shea drafted in for Damian Martinez, who is ineligible.
Tuesday's game with Schalke was given added importance following Arsenal's 2-0 defeat to the German side last month.
The north London side currently sit second in Group B, one point behind leaders Schalke.