Arsenal's Swiss defender Johan Djourou has blasted compatriot Massimo Busacca after he sent off Robin van Persie.
Referee Busacca controversially gave Van Persie his marching orders after he shot at goal just a second after the whistle had been blown for offside in Tuesday's UEFA Champions League clash.
The score at Camp Nou was 1-1 at the time with Arsenal on course to qualify, but the Catalans went on to win 3-1 and progress into the quarter-finals of the competition.
Djourou told the Daily Star: "I am Swiss and the referee was Swiss. I feel a sense of shame.
"He had no right to take a decision of that kind. It changed the course of the game.
"At this level of football you can not accept decisions like that.
"But you have to be honest and admit Barcelona deserved their win. Lionel Messi is an exceptional footballer, all the more so when he plays at home, and he does some amazing things.
"It is really hard to mark him. We succeeded in the first half. We were very compact and it was a real pity that we conceded just before the break."
But Busacca has a fan in the shape of Manchester United defender Rio Ferdinand, whose side face the Gunners in their FA Cup quarter-final at Old Trafford on Saturday.
Ferdinand said on Twitter that the Swiss was "the best referee about" before Van Persie's dismissal and afterwards added: "My comment about the referee was about an hour ago, before the red card. Still the best ref for me."