Goalkeeper Wojciech Szczesny has been ruled out of Arsenal's Champions League trip to French side Montpellier with an ankle injury.
The Poland international, 22, only returned to the Gunners' side for Saturday's 6-1 thumping of Premier League newcomers Southampton following a rib injury.
He will again be replaced by Italian shot-stopper Vito Mannone, who impressed during Szczesny's earlier absence by keeping clean sheets against Stoke and Liverpool.
Arsenal boss Arsene Wenger insisted Szczesny was still his first-choice goalkeeper following the Saints clash, despite his mistake allowing Danny Fox to score a consolation for the visitors.
Youngster James Shea is expected to be handed a place on the bench against French champions Montpellier at the Stade de la Mosson.