Portugal winger Ricardo Quaresma is doubtful for his team's Euro 2016 Group F opener against Iceland on Tuesday due to a muscular injury.

The Besiktas player missed training on Sunday and according to Portuguese media, tests conducted on Quaresma's right leg revealed a minor problem with the 32-year-old set to undergo a fitness test on Monday afternoon.

Portugal, coached by Fernando Santos, will hold a training session at St Etienne's Stade Geoffrey-Guichard later on Monday, the same venue where they will face Iceland.

Quaresma scored twice and set up two more goals in his national team's 7-0 demolition of Estonia last week, Portugal's final warm-up game for the tournament in France.

Should Quaresma fail to pass the fitness test, Fenerbahce winger Nani is expected to take his place in the starting side, alongside former Manchester United team mate Cristiano Ronaldo in the attack.

Nani started just one of Portugal's three warm-up games, a 1-0 defeat to England on June 2 and was replaced by Quaresma after 61 minutes.