Bento: Winner could come from Group of Death
Portugal are braced for tough battles in Group B but Bento remains confident.
"We have a very clear objective, first to get to the quarter-finals of this great competition which is Euro 2012, then, naturally, to try and go as far as possible," the coach told journalists.
"It would not be surprising to see the next European champions coming out of our group."
His squad announcement included call-ups for the promising Oliveira and the Braga duo of Custodio and Miguel Lopes.
"We are taking Nelson who is a player with different characteristics from the other strikers, one whose path in the national team has been one of constant climb which earned him a place in his club," Bento said.
Oliveira emerged into the spotlight at the last under-20 World Cup where he scored four goals as Portugal reached the final. He has been dubbed Portugal's Eric Cantona and will dispute a place up-front with Zaragoza's Helder Postiga and Hugo Almeida of Besiktas.
"Nelson is a young man with great quality, potential and we will logically try to make him useful for us."
Bento was speaking in the medieval town of Obidos where Portugal will hold their training camp between May 21 and June 2 before leaving for Opalenica, their headquarters in Poland.
Goalkeepers: Rui Patricio (Sporting), Eduardo (Benfica), Beto (Cluj)
Defenders: Joao Pereira (Sporting), Bruno Alves (Zenit St Petersburg), Fabio Coentrao (Real Madrid), Pepe (Real Madrid), Ricardo Costa (Valencia), Rolando (Porto), Miguel Lopes (Braga)
Midfielders: Carlos Martins (Granada), Joao Moutinho (Porto), Miguel Veloso (Genoa), Raul Meireles (Chelsea), Ruben Micael (Zaragoza), Custodio (Braga)
Forwards: Cristiano Ronaldo (Real Madrid), Hugo Almeida (Besiktas), Helder Postiga (Zaragoza), Nani (Manchester United), Nelson Oliveira (Benfica), Ricardo Quaresma (Besiktas), Silvestre Varela (Porto).