Lionel Messi has failed to turn up for obligatory COVID-19 testing at Barcelona, Spanish media reported on Sunday.
The 33-year-old missed an appointment, meaning that he will not be able to take part in the first training session ahead of the new season, according to safety rules of the Primera Division.
The no-show heightens the conflict between player and club.
Messi wants to leave Barca on a free transfer, citing a clause in his contract that apparently allows him to do so shortly before the end of a season.
Barca counter that the deadline for such an action expired on June 10.
According to them, Messi's contract - which runs until June 2021 - stipulates that he has to express his desire to leave 20 days before the end of the season.
Aside from Messi, players deemed surplus to requirements by new Barca boss Ronald Koeman turned up to be tested.
Among them were attacker Luis Suarez, who is being linked with Juventus, Arturo Vidal and Ivan Rakitic, who is rumoured to be moving back to Sevilla.