 Despite the ongoing transfer situation, Mathieu remained civil in regards to playing.He made 31 league appearances during the 2008–09 season, contributing to Toulouse's successful league campaign, as well as the team's success in the Coupe de France, where they were eliminated in the semi-finals by the eventual champions Guingamp.On 10 June 2009, it was announced that Mathieu would be Unai Emery's first signing of the summer after Spanish club Valencia CF secured the left back on a three-year deal.