Sidnei was used intermittently during his first season in Portugal, but still managed to appear in 24 Primeira Liga games and score three goals in as many wins, including the 2–0 derby home win against Sporting Clube de Portugal on 27 September 2008. In November, Benfica bought another 50% of his rights for €2 million, and GestiFute acquired the rights to receive 30% from any future transfer. He played in only five league matches during the following campaign – ten overall appearances – as the club won the national championship after a five-year wait.