The playmaker has begun pre-season training with his club, while Batista and 14 of the 18 squad players flew to Japan on Tuesday, against whom they will play a friendly on July 29.

Mallorca defender Federico Fazio and midfielders Javier Mascherano (Liverpool) and Lautaro Acosta (Sevilla) are scheduled to join the squad on Wednesday, and Batista hopes Messi will be arriving too.

"The technical staff and the Argentinian FA are sure Barcelona must release Messi," the coach said.

"We started to have doubts because of the situation but I know he wants to play for the national team and I hope this problem (with his club) does not affect his chances of doing so.

"Leo is a very important player for the team and Barcelona must understand they are obliged to let him play.

"But if he doesn't come, we have first-class players to use instead."

Villarreal striker Marco Ruben, who played on loan at Recreativo Huelva last season, is expected to replace Messi should Barcelona not release him.