Arsenal manager Arsene Wenger has cited the loss of Eric Abidal as the key reason for Barcelona's poor run of form.

Wenger believes that there are several factors responsible for Barcelona's downturn in form which has seen them dumped out of the Champions League and effectively lose the La Liga title to Real Madrid, but stresses the importance of the departure of Abidal for a liver transplant operation.

"I believe as well that they could not afford to lose two players - one Messi and two, Abidal. When they lost Abidal... when you watch the game when we won 2-1 he saved three goals - he made three desperate saves," Wenger told Arsenal's official website.

"Against Chelsea the other night, the bad luck was they lost Pique early in the game. They played with one defender - Puyol - in the whole game.

"Mascherano is a midfielder and Alves is a... something more than a defender. Basically they played the whole game with one defender. But they are still the best team."

Barcelona, who sit second in La Liga, were hit with the news on Friday that manager Pep Guardiola will leave the club at the end of the season.