Benfica midfielder Renato Sanches was given his first Portugal call-up on Friday, less than six months after his professional debut.
Sanches is already being chased by some of Europe's biggest clubs, according to media reports, with Manchester United and Real Madrid said to be closely monitoring the midfielder.
The 18-year-old, who has been outstanding for Benfica since making his debut in October, was included in the squad named by coach Fernando Santos for the friendlies against Bulgaria and Belgium this month.
"We are going to have a chance to look at him closely, in the day-to-day work, which involves much more than what happens on the pitch," said Santos.
Cristiano Ronaldo, who was rested for last November's friendly against Russia, was recalled along with forward Eder, midfielders Adrien Silva and Andre Gomes and 37-year-old defender Ricardo Carvalho.
"This is definitely not the final list for the Euros," said Santos.
Portugal, who face Iceland, Austria and Hungary in the group stage of this year's European Championships in France, host Bulgaria on March 25 and visit Belgium four days later.
Goalkeepers: Anthony Lopes (Olympique Lyon), Eduardo (Dinamo Zagreb), Rui Patricio (Sporting)
Defenders: Bruno Alves (Fenerbahce), Cedric (Southampton), Jose Fonte (Southampton), Eliseu (Benfica), Pepe (Real Madrid), Raphael Guerreiro (Lorient), Ricardo Carvalho (Monaco),Vieirinha (VfL Wolfsburg)
Midfielders: Adrien Silva (Sporting), Joao Mario (Sporting), William Carvalho (Sporting), Andre Gomes (Valencia), Bernardo Silva (Monaco), Danilo Pereira (Porto), Renato Sanches (Benfica)
Forwards: Cristiano Ronaldo (Real Madrid), Danny (Zenit St Petersburg), Eder (Lille), Nani (Fenerbahce), Rafa (Braga),Ricardo Quaresma (Besiktas)