On 11 October 2003, Landreau had an operation on his articular disk which was a serious injury in his football career. On 22 November 2003, Landreau made his return in a 3–1 win over his (first match in his career) against Bastia. In the semi-final of the 2004 French Cup, Landreau produced several saves, but to no avail as the team could not score and were eliminated from the competition. In the final of Coupe de la Ligue against Sochaux-Montbéliard, the match was 1–1 and played until the penalty shootout. Landreau shot the seventh penalty in a panenka style, only to be saved by Teddy Richert. Nantes were about to lose the game when Pascal Delhommeau missed, allowing Benoît Pedretti to score the winning penalty. After the match, Landreau said he had "no regrets" on missing the penalty in that manner.