Barcelona's Argentine forward Lionel Messi gestures during the Spanish league football match be tween FC Barcelona and Levante UD at the Camp Nou stadium in Barcelona, on Feb 2, 2020. (LLUIS GENE / AFP)

MADRID - FC Barcelona face a difficult Copa del Rey quarterfinal away to Athletic Club Bilbao on Thursday in the middle of a very public argument between Director of Sport, Eric Abidal and star player Leo Messi.

The argument surfaced on Tuesday after Messi reacted to an interview Abidal gave to the Diario Sport newspaper, in which he said Ernesto Valverde had been sacked as coach on January 13th because "a lot of players were not satisfied and they were not working very much."

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This drew an angry response from the striker who used a rare foray into social media to tell Abidal: "if you are going to talk about players, you have to give names, otherwise you stain all of us," adding that "those in the sporting direction of the club also have to accept their responsibility."

If you are going to talk about players, you have to give names, otherwise you stain all of us

Leo Messi

The spat has led to talk of crisis at the club on the eve of what promises to be a thrilling Copa del Rey quarterfinal between the two sides who have won the trophy the most times.

Athletic Club's 53,000 capacity San Mames Stadium is sold out with fans hoping to see a repeat of the 1-0 win the Basque side inflicted on Barca in the opening Liga Santander game of the season.

The scorer of that goal, veteran striker Aritz Aduriz, returned from injury in Athletic's defeat to Getafe on Sunday, but is clearly set for the Cup, saying "it is a wonderful challenge" to try and beat Barca. "It is the option that nobody else has got," he added.

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Barcelona's French football director Eric Abidal speaks during the official presentation of the club's new Dutch midfielder Frenkie de Jong at the Camp Nou stadium in Barcelona on July 5, 2019. (LLUIS GENE / AFP)

Aduriz will probably start on the bench for Athletic with Inaki Williams and Raul Garcia leading the attack, while Antoine Griezmann and Messi (who has missed his side's last three matches against Athletic) will lead the line for Barca, who have a doubt over central midfielder Arturo Vidal with a muscle problem, while Samuel Umtiti may not travel as he has a court case in Barcelona on Thursday.

Thursday's second quarterfinal sees Real Madrid at home to Real Sociedad. Eden Hazard and Gareth Bale could be back in the Madrid squad, while the visitors will place faith in striker Alexander Isak, who has scored four goals in his last three games, and Martin Odegaard, who is on loan from Madrid.