Tomas Rosicky has undergone knee surgery and is likely to be out of action for around eight weeks.
The Arsenal midfielder suffered the damage while playing for the Czech Republic against Iceland on 12 June, in a Euro 2016 qualifier that his team lost 2-1. It held him back in pre-season, to the extent that he played no part.
The 34-year-old, who agreed a new one-year contract at Arsenal last season, was forced to have arthroscopic surgery on 4 August, according Pavel Paska, his agent. Paska put his likely absence at between four and eight weeks, and it is expected to be at the top end of that scale.
Arsène Wenger, the Arsenal manager, hopes to have Héctor Bellerín available for Sunday’s visit to Crystal Palace. The full-back was ruled out of last Sunday’s 2-0 home defeat to West Ham with a slight thigh injury, but he has returned to training.