Oliveira, who is 19 years old, has not yet made his debut for Benfica's first team, but is highly regarded within Portuguese football.
Deco is aware of Oliveira's potential and has initiated discussions with the player's agents, Carlos Gonçalves and Antonio Casanova, about a possible transfer to Spain.
Oliveira has gained international experience, having made two appearances for Portugal's U21 team.
His contract with Benfica is set to expire in the summer of 2027.