Arsenal captain Laurent Koscielny did not break his jaw in Friday's FA Cup defeat to Manchester United, but Sokratis Papastathopoulos is set to be out until late February.
Koscielny had to receive extensive treatment after receiving a boot to the face in a collision with Romelu Lukaku during the second half of the fourth-round tie.
Unai Emery revealed in a post-match news conference that he feared Koscielny had broken his jaw, but Arsenal have now confirmed that the France international suffered bruising and soft tissue damage.
No timescale has yet been put on the centre-back's return, although French publication L'Equipe have reported that the 33-year-old, who missed the first half of the season after suffering a ruptured Achilles at the end of last term, will still require surgery.
Koscielny's injury was the second Arsenal suffered in Friday's encounter, with fellow defender Sokratis having been forced off with an injury to his left ankle during the first half.
Emery seemed to indicate that Sokratis' injury was less serious, but Arsenal are not expecting the former Borussia Dortmund man to return to full training until the end of February.
The Gunners have been plagued by defensive injuries this season, with Hector Bellerin and Rob Holding both long-term absentees, with Matteo Guendouzi having to deputise at centre-back alongside Shkodran Mustafi for the final stages of the United defeat.
