In July 2008, he was signed by A.C. Siena in co-ownership deal, for €1.2 million, However, after just played one league match for Siena in 2008–09 Serie A, Belmonte returned to A.S. Bari on loan. In the first season he played a few games, as the team had Leonardo Bonucci and Andrea Ranocchia as centre-backs.