Arsenal's Fabio Vieira could be experiencing issues with his health this summer.
The Portugal under-21 star was expected to play at the U21 European Championships.
However, Vieira is set to miss the tournament, as he has an unknown medical condition.
Per Mais Futebol, he has been forced to drop out, with Benfica's 18-year-old talent Diego Moreira taking his place.
Vieira had an evaluation with the Health and Performance Unit at Portugal, with a decision made that he should withdraw.
One who will be with Portugal's under-21 side this summer is Arsenal left-back Nuno Tavares.