The Spanish giants are reportedly keeping an eye on the young striker, who has become an important part of the Portuguese club this season
The Catalan club dispatched a scout to check on the 20-year-old during his side's 2-0 Champions League victory against Zenit St Petersburg on Tuesday, which earned the Portuguese club passage into the last-eight stage.
Oliveira, who scored Benfica's second goal of the night, is widely considered to be one of the hottest prospects in Portugal and he played a leading role in the Seleccao's runners-up finish at the Under-20 World Cup last summer.
He broke into Benfica's senior ranks this season after spending 2010-11 on loan at Pacos de Ferreira, and has scored three goals to date for the Lisbon-based club.
His club performances caught the eye of Portugal coach Paulo Bento, who gave the striker his first-ever cap last week in the goalless draw against Poland in a friendly international.
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