Arsenal centre-back Per Mertesacker has had a go at his Arsenal teammates following the embarrassing 3-2 loss at home to Greek side Olympiacos Tuesday night, admitting that they deserved to have lost the match due to the commitment they showed while defending.



He said: “We lacked that concentration and it is not understandable why we drifted and did not do the job we are used to doing.



“That is not acceptable and we will be punished [for that] in the Champions League.



“We need to get behind the ball and play better defensively.



“We lacked discipline, even when you get a goal back don’t rush yourself.



“Get your discipline back and with possession you get your chances. If we are not disciplined and do not chase the ball we have got no chance.”



Arsenal must now play league leaders Manchester United on Sunday, and will be without key player Laurent Koscielny after the Frenchman suffered a hamstring injury which could now keep him out of action for several weeks.



German World Cup winner Mertesacker added that if the team did not learn from their mistakes in Europe their entire season could collapse around them.



“We have got a couple of days to look back on that performance. I think everyone will have regrets and it is good to take that away.



“It will take a couple of days to recover and to think about Manchester United and play in a different competition, which will be a good opportunity to come back to the Emirates and play our football with possession and dynamism.”