Fabio Coentrao says he asked not to be selected in Portugal's squad for the World Cup due to being left physically exhausted by a "very tiring" season.

The 30-year-old, who spent the 2017-18 season playing for Sporting CP on loan from Real Madrid, has featured for Portugal at each of the last two World Cups.

But the left-back confirmed in an Instagram post he told Portugal coach Fernando Santos not to call him up for the group heading to Russia.

"Last week, after a lot of consideration, I told the national team that after a very tiring season, I feel I am not in the conditions required to represent the Selecao at the World Cup," Coentrao said.

"I will never turn my back on my country, and hope to be able to represent our national team more often in the future.

"Until then, I am and I will always be one to cheer on the outside, see you soon. Good luck guys."

Coentrao started 25 league games as Sporting finished third in the Primeira Liga, behind champions Porto and Benfica, while he made a further 18 appearances in domestic and European cup competitions.

Santos has named a preliminary squad of 35 players for the World Cup, leaving out Euro 2016 winner Renato Sanches, and is set to trim the group to a final 23 on Thursday.

Portugal open their World Cup campaign with an Iberian derby against Spain on June 15 before facing Morocco and Iran in their remaining Group B games.