The Gunners, already missing Johan Djourou and Kieran Gibbs at the back, are suffering an extensive early season injury bug that could worsen with Frenchman's substitution
Manager Arsene Wenger is already missing Johan Djourou, Kieran Gibbs and Armand Traore in defence, with Jack Wilshere and Abou Diaby also sidelined. Gervinho and Alex Song are also unavailable, with both serving three match suspensions.
Koscielny was taken off after going down with what Sky Sports reported as back spasms 15 minutes into the game at the Emirates Stadium. The centre-back was running with the ball innocuously when he suddenly went to ground in clear pain.
Liverpool striker Andy Carroll had been penalised for a push to the back of Koscielny minutes earlier but the incident seemed to have no effect on the Frenchman at the time.
The 18-year-old Spaniard Ignasi Miquel was thrown into the fray as Koscielny's replacement, with the Arsenal defence already featuring the inexperienced Carl Jenkinson, who started the match at right-back.