Arsenal fullback Bacary Sagna suffered a broken leg in their derby defeat to Tottenham.
Sagna was taken off the pitch on a stretcher after falling badly in the 68th minute and news of the break was later revealed by the French Football Federation.
Sagna joins an injury list at the Emirates that already includes Jack Wilshere, Thomas Vermaelen, Abou Diaby and Johan Djourou.
Carl Jenkinson, a summer signing from Charlton, came on for Sagna against Spurs and could now be set for an extended run in the first team.