Following the departure of Jens Lehmann in the summer of 2008, Mannone became Arsenal's third-choice goalkeeper, behind Manuel Almunia and Łukasz Fabiański. Mannone changed his shirt number from 40 to 24 at the beginning of the 2008–09 season, after Manuel Almunia (the previous owner) was given the number 1. On 19 July 2008, he was brought on for the second half of Arsenal's 2–1 pre-season friendly win over Barnet at Underhill, keeping a clean sheet. He made a total of four pre-season appearances for Arsenal's first team in the summer of 2008, coming on as a half-time substitute in all of them.