Arsenal could be without leading scorer Robin van Persie for a month after the Holland striker suffered a knee injury on international duty last night.
Van Persie - who has scored five goals in his last four appearance for the Gunners - could miss the Champions League game with Slavia Prague as well as league games at Liverpool and at home to Manchester United.
"It looks like a knee injury," said manager Arsene Wenger. "We will know later today how bad it is, but the early signs are that he will not be able to perform for us in the next four weeks.
"It is a big blow. Robin is a striker, a supportive striker and important on set-pieces as well. I hope he will be back soon and we'll do the maximum to get him back."
Swiss defender Philippe Senderos (back) is also set to be out for a fortnight but captain William Gallas, Jens Lehmann and Tomas Rosicky should all return to contention for Saturday's game against Bolton.