Arsenal manager Arsene Wenger has revealed that defender Laurent Koscielny could not feature again for the Gunners in October.
The Frenchman suffered a hamstring injury in mid-week against Olympiakos and will miss Sunday's Premier League clash against Manchester United.
Midfielders Mathieu Flamini and Mikel Arteta are also ruled out but Francis Coquelin is expected to start at the heart of the Arsenal midfield.
"Laurent Koscielny will certainly be out," Wenger said on Friday.
"He has a hamstring strain and it looks like it will be three weeks, something like that.
"Both [Mathieu Flamini and Mikel Arteta] are out [but] Francis [Coquelin] should be okay for Sunday, yes."