Celtic goalkeeper Artur Boruc blamed himself for the goal which sunk his side's chances of recovering their UEFA Champions League last-16 tie against Barcelona.
The Catalan club went in to the match leading 3-2 from the first game in Glasgow and when Xavi knocked home Sylvinho's cross after just three minutes the tie was all but over.
The Poland international pulled off a string of saves to prevent the visitors suffering a more comprehensive beating but after the match he insisted that he should not have lost the crucial early goal.
He said: "We lost 1-0 and I should have done better. I wasn't good enough at the goal and the five stops don't matter.
"I should have played better and I should have saved the ball even though it moved. Nine out of 10 times I would have saved it.
"If you want to be a better player you have to improve.
"The Champions League is something special for us and hopefully we can go further in future.
"We lost our chance at Celtic Park when we lost three goals.
"I don't know if Barcelona will win the Champions League. We're not there so I don't care."
Defender Gary Caldwell, however, believes Boruc should not be too hard on himself.
He said: "Artur made a couple of stops. It was disappointing but it doesn't matter whose fault it is we needed to get in first to go through.
"It was disappointing the way we played in the first half. We stood off them and let them dictate.
"In the second half we got in their faces more.
"We could quite easily have buckled and thrown the towel in but the players in this club are not like that. We stuck to our task.
"There's a lot to learn from that. The players here can get better and the only way we can progress is by coming to places like this.
"If we improve we can go further, but maybe we need a slightly kinder draw."