Bernardo Silva is an injury concern for Portugal ahead of Thursday's World Cup qualifier with the Republic of Ireland.
The Manchester City playmaker missed Tuesday's training session with the Seleçao ahead of their trip to Dublin.
According to A Bola, the 27-year old was suffering from muscle pain but the extent of his injury was not known.
Silva was the only member of Fernando Santos' squad to miss training as they gear up for another meeting with Stephen Kenny's side.
Portugal sit second in Group A, a point behind Serbia in the race for Qatar 2022 qualification. They face Dragan Stoijkovic's side in Lisbon on Monday for what promises to be a straight shootout for top spot.
Portugal are walking a disciplinary tightrope ahead of that Estadio da Luz showdown, with six players just one yellow card away from a suspension.
Silva's City teammates Joao Cancelo and Ruben Dias, Jose Fonte, Renato Sanches, Joao Palhinha and Diogo Jota all risk missing the Serbia game if they pick up another booking.
"I hope I don't have any casualties for the Serbia game," said head coach Santos, "There are some factors that we need to consider, there are several that are on yellow cards, but I hope that's not a factor.
"I called up 26 players, which I don't normally do. It's more like 24 or 26, but I have to consider all eventualities."