Messi doubtful for Barcelona openers
Barcelona visit Athletic Bilbao in the traditional curtain raiser to the season on Sunday, and could also be without Thierry Henry and Zlatan Ibrahimovic, who are recovering from injuries.
Messi's participation in Barca's first game of the Primera Liga season, at home to Sporting Gijon on August 31, is also uncertain because Argentina face Brazil at home in a World Cup qualifier five days later.
"I will ask permission from (coach Pep) Guardiola to be with my national team," Messi was quoted as saying in Spanish media on Friday.
Barca's first league game was moved due to the European Super Cup against Shakhtar Donetsk being scheduled for Friday August 28.