Manchester United boss Sir Alex Ferguson admits he's been impressed by Barcelona this season.

Apart from Chelsea, Liverpool and Arsenal, Ferguson is convinced Barcelona will provide the main danger in the Champions League.

He said: "I place them alongside the English teams as possible winners. They have to be the big threat to everyone.

"Our experience of playing against them last season, they are a very difficult team to play against. They have changed their format this season.

"The English teams have established themselves as a consistent threat to all of the teams but Barcelona are a dangerous side."