Diaz has been with the principality-based side since 2002. He was officially promoted to the first-team for the 2008-09 Ligue 1 season and made his debut on August 30, 2008 in a 0-1 loss against Grenoble coming on as a substitute. On July 21, 2009 AC Ajaccio announced that they had signed the midfielder on loan from Monaco for the entire season. After two consecutive seasons with Metz on loan, he completed move to Nice, signing a one-year contract with the option of two years. In August 2013, he signed a two-year deal with Tours in Ligue 2.