Addition to this, formed the first bridging partnership with CA Osasuna from Spanish First Division where they exchanged marketing ideas, and each clubs' staff.
From Tigres, he was transferred to CA Osasuna of Pamplona in La Liga, but saw little action and was returned to Tigres.
His first start for the first team occurred on 12 January 2012, in a 2–1 away triumph against CA Osasuna for the season's Copa del Rey (6–1 on aggregate).
In only his third official appearance for Barcelona's first team, on 12 January 2012, Roberto scored his second goal, helping the visitors come from behind to win it 2–1 against CA Osasuna in the season's domestic cup (6–1 on aggregate).
In mid-November 2008, Sergio signed with CA Osasuna until the end of the top flight season, as the Navarrese lost Rovérsio for its duration due to a serious knee injury in a Spanish Cup contest against Getafe CF.
After only collecting seven points from the first 19 games – which led to the sacking of coach José Ángel Ziganda – the club amassed 27 in the remaining 19 with Néstor Gorosito as boss, not good enough however to prevent the drop as last (the club, however, had chances to stay up until the final round, a 1–1 draw at CA Osasuna).