Barcelona manager Quique Setien believes there are problems at clubs all round the world in response to Lionel Messi's row with Eric Abidal.
Club director Abidal claimed in a Spanish newspaper that a number of Barcelona players were not working hard enough under Ernesto Valverde, who was sacked last month.
But in a lengthy Instagram post, Messi, who played alongside Abidal, took aim at his former team-mate for his comments.
Setien was dealt a huge injury blow on Tuesday when it was confirmed that Ousmane Dembele has been ruled out for the remainder of the season.
The France international, 22, suffered a hamstring tear on his return to training, having been sidelined since November with a thigh problem.
Setien added: "I am worried not about Dembele as a footballer, but more Dembele the person. He is an extraordinary kid, and he worked with intensity and desire to come back.
"I am very sad for him because he is going to be sidelined for four to five months without football which is what he likes the most. That is what really hurts me."
Barcelona will be overwhelming favourites to win the quarter-final tie against a Bilbao side that has failed to win in their last seven league matches.
But 38-year-old striker Aritz Aduriz, now in his third spell with the club, said: "It's a wonderful challenge. When you play football, you dream of having this kind of matches.
"I hope we can have a memorable night at San Mames. One always dreams about that."