Xavi has questioned whether a “miscalculation” in the away allocation played a part in Barcelona’s Europa League exit against Eintracht Frankfurt.
The Bundesliga side were backed by a huge travelling support of around 30,000 in the Camp Nou as they shocked Barca to make the semi-finals.
Frankfurt scored three times without reply to lead 4-1 on aggregate before Barca scored two late goals to make the final scoreline more respectable.
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It is the first defeat Barca have suffered in 15 matches.
“The atmosphere has not helped us,” said Barca head coach Xavi.
“It seemed like a final with divided fans. The club is checking what has happened, it has been a miscalculation on our part.
"Today I was expecting a Camp Nou with 70,000 Barca fans, but it hasn’t been like that."
The loss means Barca look set to end the season without a trophy.
They are 12 points behind La Liga leaders Real Madrid and are not yet guaranteed a top-four finish. Barca are second in the table but fifth-placed Real Betis are only four points behind, albeit having played a game more.
“We haven't known how to attack well, we haven't played like in other games. It's a very big disappointment,” added Xavi.
“I would like to congratulate Eintracht Frankfurt because they deserved it.
“The goal for the remainder of the season is to qualify for the Champions League."
Barcelona are next in action on Monday, April 18 when they host Cadiz in La Liga.
Frankfurt face West Ham in the semi-finals after they swept past Lyon in impressive fashion.
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