The 26-year-old Argentina international was whistled by Atletico fans during their 2-2 draw with Villarreal on Sunday, following a summer in which he made public his desire to leave the club and join rivals Barcelona. Atlético said Álvarez was "unwell" on Wednesday when he failed to join his teammates in training, and a club spokesperson told ESPN that the player continued to feel ill a day later.
Barcelona president Joan Laporta has reiterated the club's interest in signing Álvarez, stating that they would be willing to sign him if Atlético were willing to sell him in this summer window. Atlético, however, have hit back with a statement, saying there was a "zero percent chance" of Álvarez joining Barcelona and calling themselves "victims" in the saga.
Atlético are next in action in LaLiga on Saturday, when they visit Sevilla. The transfer saga surrounding Álvarez continues to unfold, with no clear resolution in sight.