Arsenal defender Gael Clichy is facing a month on the sidelines after suffering a suspected stress fracture in his lower back.
The left-back is an integral member of Arsene Wenger's first XI but has been forced onto the treatment table after sustaining the injury.
France international Clichy will miss Wednesday's UEFA Champions League clash with AZ Alkmaar and the next European clash against Standard Liege on 24th November.
The problem will also keep him out of the reckoning for the forthcoming Premier League games against Wolves, Sunderland and London rivals Chelsea.
Clichy could return for the Carling Cup quarter-final meeting with Manchester City at the start of December but it is unlikely Arsene Wenger will rush him back into action.
Midfielder Tomas Rosicky returns to the squad for the Group H clash against Alkmaar at Emirates Stadium following a knee problem.
Striker Nicklas Bendtner (groin), goalkeeper Lukas Fabianski (thigh), Theo Walcott (knee) and Denilson (back) remain out.
"We have some bad news because Bendtner was quite seriously injured and on top of that we lost Gael Clichy with a back injury that was not expected," Wenger said.
"Bendtner was expected, Clichy was not expected and it looks like he could be out for a while.
"We fear a stress fracture of the back for Clichy and if that's the case he will be out for a few weeks.
"Nicklas (Bendtner) we still don't know yet but he will be out at least for four weeks."