On his Inter debut on 26 August, Vieira scored twice as the team won 4–3 against A.S. Roma in the 2006 Supercoppa Italiana at the San Siro. He later won the 2006–07, 2007–08, and 2008–09 Serie A titles. But due to injury, he failed to become a regular starter. Olivier Dacourt, initially a backup player, became manager Roberto Mancini's first choice player in the 2006–07 season. After the club signed Sulley Muntari and Thiago Motta, Vieira became of lesser and lesser importance in the team.