Tomas Rosicky will be sidelined for at least two weeks with a hamstring injury.
The midfielder was forced to miss Arsenal's crushing victory over Derby after suffering the problem against Sevilla last Wednesday.
He underwent a scan over the weekend and it has now been confirmed that he will not play again for fortnight.
Rosicky will therefore miss Arsenal's Premier League games against West Ham and Sunderland, as well as the UEFA Champions League clash with Steaua Bucharest.
There could also be doubts about his availability for Czech Republic in their upcoming Euro 2008 qualifier against Germany.
"I went through several investigations including the MRI scan and after that the doctors told me I would have to rest for at least two weeks," Rosicky said on his own personal website.
"Therefore, once again I have to rest, undergo physiotherapy and a gradual recovery.
"I must believe that there will be no more complications."