Arsène Wenger believes the loss of Eric Abidal has been a crucial factor behind Barcelona’s disappointing end to the season. The Spanish champions look set to surrender their crown after losing at home to Real Madrid last week, and exited the Champions League against Chelsea on Tuesday. Wenger believes there are a number of reasons to explain Barcelona’s downturn in form, not least the departure of Abidal for a liver transplant operation. “Personally I still think Barcelona are the best team in the world,” he said. “They play tired, because what has changed at Barcelona is they did not have the squad to play at the World Cup and in the Copa Del Rey, the Champions League and the Spanish championship. “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. “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. “Macherano 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.”