Arsene Wenger has billed the Champions League fixture against Liverpool as the start of the most challenging period he has faced in nearly 12 years in charge of the north London club.

Arsenal will play Liverpool three times over 11 days - the two legs of a Champions League quarter-final and a Premier League fixture - and then face Manchester United at Old Trafford on April 13.

"It will be the highest challenge of my career," Wenger said. "The next ten days will define our season because I strongly believe that we are in the championship race.

"This next period is vital and the impact of the first game of that sequence is also vital because it will set the tone for the rest."

Wenger has seen his side slip from the top of the league to third after a run of four draws and one defeat that Arsenal finally ended on Saturday when they overcame a two-goal deficit to beat Bolton Wanderers 3-2 despite having a player sent off.

"We have the belief that we can beat anybody in any competition," Wenger said. "If it is Liverpool or anyone else we want to get that into the game. It is true we had a little dip recently but our victory at Bolton did us a lot of good because when you continue to play well but not win your confidence suffers.

"That was very important that we got our confidence back but also that our mental strength is rewarded because that is what we needed in the game against Bolton."

Wenger is expecting a cagey match in their first leg against Liverpool on Wednesday "for the simple reason that there is a knockout situation."

"We are on the train and we want to stay on it. One of us has to go out but Liverpoool certainly will make it tight and play on the break more than in the championship, where you can concede a goal and still continue.

"Every goal is so vital in the knockout stage that the focus is naturally a bit higher, the intensity is also naturally a bit higher."

Wenger also acknowledged that the employment of a Dutch rather than an English referee could affect the pattern of the game. "They are a bit more interventionist on the continent so the fluency of the British game could go, but I don't mind.

"Before a game it is never important for me who is the referee. You just focus and prepare well and get your team to play the game you want to play."