European champions Portugal will take on Switzerland in their opening 2018 World Cup qualifier without rising Bayern Munich star Renato Sanches, the Portuguese federation said on Monday.

The 19-year-old midfielder who moved to Germany after a sensational season with Benfica and a thrilling showing at Euro 2016 has a torn thigh muscle.

Originally included in coach Fernando Santos' squad for the September 1st friendly with Gibraltar and the September 6th World Cup opener in Basel, but after talks between Bayern and Portugal medical staff he was left out.

The speedy winger with an eye for goal sustained his injury three weeks ago and has only just resumed training with the Bavarian giants.

Portugal are also without injured captain Cristiano Ronaldo who continues to recover from his injury sustained in the 1-0 final victory over France at Euro 2016.