He represented Cameroon at international level. His most notable moment with the Lions Indomptables was at the 2003 FIFA Confederations Cup, where he became the starter central midfielder in the lost final against host France, after replacing the late Marc-Vivien Foé during the victorious semi final versus Colombia.
In 2003, he was involved in a serious car crash which ruled him out of the game for four months. Despite this, he fought back to reclaim his form and his performances attracted the attention of Harry Redknapp, with Mézague joining Portsmouth F.C. on loan for the 2004–05 season. However, he failed to make any sort of substantial impression and returned to France in June 2005, where he followed his former manager at Portsmouth Alain Perrin to FC Sochaux-Montbéliard.