By Wayne Veysey

2nd Oct, 2015 | 10:52am

Laurent Koscielny injury will sideline him for three weeks

By Arsenal correspondent Tony Hughes
Laurent Koscielny will be out for three weeks with a hamstring injury, according to Arsene Wenger.
The France international limped out of Arsenal’s 3-2 Champions League defeat to Olympiakos in midweek at the 57-minute mark.
Wenger confirmed at his weekly media briefing on Friday that Koscielny will miss the Gunners’ clash against Manchester United at Emirates Stadium. He will be joined on the sidelines by injured midfield duo Mikel Arteta and Mathieu Flamini.
“Koscielny will certainly be out. He has a hamstring strain, it looks like three weeks. Arteta and Flamini are out.”
Koscielny’s absence against Premier League leaders United will mean a recall for Per Mertesacker, who replaced his team-mate against Olympiakos
The German has slipped down the Arsenal centre-back pecking order this season following the emergence of Gabriel, who is available for domestic action after serving a one-match suspension.
Mertesacker and Gabriel are set to be paired at the back against United on Sunday, with Petr Cech returning to the team in goal after being surprisingly left out of the Olympiakos match.
Cech was replaced by David Ospina in midweek but the Colombian was at fault for the Greek team’s second goal when he spilt a corner over his goal-line.