Sergio Ramos said Wednesday that Lionel Messi should be allowed to decide on his future as the Argentine superstar attempts to force his way out of Barcelona after two decades at the club.

"He has earned the right to decide his future. I don't know if he is doing it in the best way," Ramos said ahead of Spain's opening UEFA Nations League clash with Germany in Stuttgart.

"For Spanish football, for Barca and for us who like to beat the best, we would like him to stay."

Ramos has been one of Messi's fiercest rivals as Barca have battled it out for domestic and European dominance with the Spain captain's club side Real Madrid.

The pair are roughly the same age and have both won a host of major honours as their teams shared the La Liga title almost uninterrupted over the last 16 seasons.

The 34-year-old centre-back said that the departure of one of the greatest ever players would be a big blow for Spanish football.

"Leo makes the Spanish League and his team better, he makes the Clasicos more beautiful because you like to win while being against the best and he is one of the best in the world.

"He has earned the right to decide for himself."

Messi, who has been at Barca since he was 13, is in a stand-off with the Catalan giants which is threatening to descend into an expensive and bitter legal battle as the club insist a 700 million-euro ($833 million) release clause needs to be activated before he be allowed to leave.

Messi boycotted Barcelona's first pre-season training session on Monday and also failed to attend a coronavirus test at Barcelona's training ground on Sunday.

He and his lawyers argue he is allowed to go for free this summer according to another clause in his contract, which they claim was triggered on August 25 when a fax stating Messi's intention to leave arrived at Camp Nou.

Abu Dhabi-owned Manchester City are the firm favourites to sign Messi, partly due to his previous success with City coach Pep Guardiola.