On 1 July 2007, Guarente's transfer back to Atalanta was officially completed. The 2007–08 Serie A campaign was his debut season in the top flight of Italian football.
The transfer of Guarente back to Atalanta on 1 July 2007 was formally completed, launching his first foray into Italy's top-tier football competition, which commenced with the 2007–08 Serie A season.