By Giuseppe Muro

The Champions League becomes a different competition once it enters the knockout stage, according to Arsène Wenger.

Arsenal ensured their passage to the last 16 with a 3-1 victory over Partizan Belgrade on Wednesday night despite suffering slip-ups against both Shakhtar and Braga during their Group H schedule.

Wenger knows his team can afford no more mistakes as the league format is replaced by two-legged ties.

“Now in the last 16 it becomes a different competition,” he said. “It becomes a cup competition.

“Until now it has been a championship and now we go into a real cup mode and that means for 180 minutes you have to be at your best.

“Last year we went out against Barcelona. I feel we had some room to do better because it was 2-2 at home and over there we were leading 1-0 before we lost 4-1.

“It depends whether you have your best players available, whether we have a good level of confidence then. It is very difficult to predict how far you can go.”

Copyright 2014 The Arsenal Football Club plc. Permission to use quotations from this article is granted subject to appropriate credit being given to www.arsenal.com as the source 9 Dec 2010