Roberto
Arsenal have to take the game to OlympiacosGetty

Arsene Wenger believes that Arsenal have to go for it from the start against Olympiacos if they have to have any chance of qualifying for the knockout stages of the Champions League. The Gunners have to win by a margin of two goals or match Olympiacos' score at the Emirates to progress, which will be a tough ask, if their performance against Sunderland is any indicator.

The Gunners struggled to break down the Black Cats and rode their luck at times, with the visitors spurning a series of gilt-edged opportunities in both halves to take the lead. The Gunners broke the deadlock through Joel Campbell but surrendered the advantage with an own goal by Olivier Giroud in the dying minutes of the first half. Giroud scored the second goal for the Gunners to ease the pressure while Aaron Ramsey scored the third to put the result beyond doubt.

A similar performance against Olympiacos will spell doom for the north London club, who have tasted defeat in each of their last three trips to that terrain. However, Wenger is aware of the task at hand and insists that the performance against Sunderland was down to a lack of confidence, having failed to win their last three games and the need to find some balance after incorporating a host of new players into the squad following injury problems.

"There is one positive thing for us - we know exactly what we have to do. We know that we have to go for it from the start. So let's do that and hopefully we can get through. We know what is expected and we have studied Olympiacos," Arsene Wenger told Arsenal's official website.

"We changed the team completely [against Sunderland] because we've lost the core in midfield of Santi Cazorla and Francis Coquelin in the past two weeks, and we had to find a new balance. We were a bit insecure as well because we had not won last week. I believe [Olympiacos] is a different game psychologically, it's clear, we just have to go for it."