Diana was used irregularly by the Emilia-Romagna side, winning the Italian Cup in his first season, but hardly featuring at all in 2002–03. In January 2003 he moved on loan to Reggina Calcio along with Emiliano Bonazzoli, posteriorly signing for U.C. Sampdoria at the end of the campaign. A key member from the start for the Genovese, he helped the team qualify for the UEFA Cup in his second year, scoring five goals in 32 matches; in early May 2005 he scored the game's only at Juventus F.C. and, the following week, also found the net, in a 3–0 home success against ACF Fiorentina.