He quickly made a name for himself at the club, breaking into the first team in 2007 and contributing largely to a promotion to the Série A, scoring 18 goals in 28 games – season's best – and being voted the competition's best player.

[3] It was this form which initially prompted Brazilian under-20 coach Nélson Rodrigues to include Diogo in his team (he had already played in previous national youth sides).

[4] Early in the same year, president Manuel da Lupa said he was as good as if not better than AC Milan's teenage sensation Alexandre Pato; he added that the player had only shown 50% of his capability due to consistent injuries.

[5] In July 2008, several teams had been attracted to Diogo's talents, and the player revealed his desire to play his trade in Europe after longtime admirers Arsenal were joined by ACF Fiorentina in bidding for his services.

He had been monitored by the former's scouting department for more than two years, and offers included a £9,000,000 one, promptly rejected by Portuguesa;[6] Arsenal manager Arsène Wenger also publicly stated that he had tried to sign him once, as a 16-year-old.

also became interested and, in a widely documented and somewhat controversial period of negotiation, Diogo finally signed for the Greek club in August 2008, for €9 million and 70% of the player's rights.

[14] Diogo's second season was disastrous for both him and the team, suffering several injuries which limited to just slightly more than half of the games, scoring just two goals and losing his place in the starting lineup to Kostantinos Mitroglou.

In the competition's next round, however, against Maccabi Tel Aviv FC, he was sent off after punching opposing goalkeeper Liran Strauber, in a 1–0 away loss that also meant the Greeks' elimination on the away goals rule.