Arsene Wenger has confirmed that Arsenal will be without Laurent Koscielny for the game against Manchester United on Sunday.

The defender picked up the problem against Olympiacos on Tuesday night and will now be sidelined for around three weeks with the strain.

LONDON, ENGLAND - SEPTEMBER 29: Per Mertesacker of Arsenal comes on as a substitute for Laurent Koscielny during the UEFA Champions League Group F match between Arsenal FC and Olympiacos FC at the Emirates Stadium on September 29, 2015 in London, United Kingdom. (Photo by Shaun Botterill/Getty Images)
LONDON, ENGLAND – SEPTEMBER 29: Per Mertesacker of Arsenal comes on as a substitute for Laurent Koscielny during the UEFA Champions League Group F match between Arsenal FC and Olympiacos FC at the Emirates Stadium on September 29, 2015 in London, United Kingdom. (Photo by Shaun Botterill/Getty Images)

The boss also confirmed that Mathieu Flamini (hamstring) and Mikel Arteta (nobody knows) will also miss out.

Wenger told the press at his pre-match press conferenceĀ “Koscielny will certainly be out. He has a hamstring strain – it looks like three weeks. Arteta and Flamini are out.”

In contrast, United have no new problems after their midweek match and are set to welcome Michael Carrick back into the side for the six-pointer at the Emirates.

Arsenal are also without Jack Wilshere and Danny Welbeck but Petr Cech, who allegedly had a minor strain at the start of the week, will come back into the side to replace Calamity Dave.