Sporting CP midfielder Joao Mario is a natural replacement for Andres Iniesta at Barcelona, according to Paulo Futre.
The 23-year-old Portugal international has been linked with a move away, with numerous Premier League clubs reportedly interested.
His dad and agent raised concerns over the midfielder's wages at Sporting, leading to further speculation about his future.
Futre, a Ballon d'Or runner-up in 1987, feels Joao Mario is the only player capable of eventually replacing Barca star and veteran Iniesta.
"For me, Joao Mario must always play for Portugal," he told Agencia Lusa.
"He is the most important player in the Portuguese league, with Jonas at Benfica.
"If he does not stop improving, within two years he is the only player in Europe to replace Iniesta at Barcelona.
"With the quality and game intelligence he has, he is a natural replacement for Iniesta."
Joao Mario is part of the Euro 2016 squad as Portugal prepare to face Iceland, Austria and Hungary in Group F.