Xavi admitted his Barcelona team failed to match the intensity of Athletic Bilbao as they tumbled out of the Copa del Rey at the last-16 stage, another blow in a dismal season.

Barcelona may yet claw their way into the Champions League places in LaLiga, but their trophy pursuit looks doomed to failure. Beaten by Real Madrid last week in the Supercopa semi-finals, a 3-2 defeat after extra time against Athletic on Thursday was another bitter pill for head coach Xavi and his players.

Add in the blow of losing substitute Ansu Fati to what Barcelona described as "a femoral biceps injury in his left thigh", and it was a calamitous night at San Mames for the visitors.

Barca are out of the LaLiga title reckoning, and Europa League play-off opponents Napoli will surely fancy their chances of taking the Blaugrana's scalp on this latest evidence.

The defeat in Bilbao, where home captain Iker Muniain capped an inspiring performance with two goals, means Barcelona have failed to reach at least the quarter-final stage of the Copa del Rey for the first time since 2009-10.

This is also the first season since 2003-04, when they were in the UEFA Cup, that Barcelona have not featured in the Champions League knockout rounds. A group-stage exit saw to that.

Barcelona got what they deserved in Bilbao. The expected goals (xG) calculation, based on each team's chances, showed the gulf between these sides was wider than the final scoreline.

Athletic had an xG of 3.33, while Barcelona's was a miniscule 0.36. The home side had 19 shots to just seven by Xavi's team, and the 66.7 per cent of possession that Barcelona enjoyed was mostly lacking in end product.

Success has flooded into the Catalan giants in recent years, and Barcelona beat Athletic 4-0 in the Copa final only last April. Lionel Messi scored twice in that game, and Antoine Griezmann also netted. Both have now long since departed.

"In summary, I think Athletic's intensity surpassed ours," said Xavi. "In duels, in second balls. They lived each ball as if it were their last."

Athletic led through Muniain and Inigo Martinez, but Ferran Torres, with his first Barcelona goal, and Pedri, deep into stoppage time, replied for Barcelona.

A handball by Jordi Alba was punished by Muniain from the penalty spot near the end of the first half of extra time, and this time Athletic did not relinquish their lead.

"With Pedri's goal it seemed like it was our moment," Xavi said, speaking at a post-match news conference.

Muniain's penalty told the coach different, however.

"It seems that when things are heads or tails, we always get tails. We have to change the dynamic," Xavi added.

He was not minded to contest the penalty decision after the final whistle. Alba was struck on the arm by Nico Williams' cross, and with VAR guidance it was an obvious spot-kick.

Former Al Sadd boss Xavi, who took over the Barcelona top job in November, said his team would "fight" for their remaining objectives.

It remains to be seen when Fati is seen again in action. He looked distressed, tearful, on leaving the pitch barely half an hour after entering the action. That setback compounded the misery of a regrettable evening.

Speaking to Barca TV, Xavi said: "We need to continue believing in this project, continue in LaLiga and continue in the Europa League. This is the way, continue to keep going and working hard."