 Brecht Wallis started training in judo at the age of 12 and a few years later moved on to Muay Thai.In 2001 he moved to the Netherlands to pursue his professional career at the Siam Gym under trainer Miki Benazzouz.He made his K-1 debut in 2003 at K-1 Holland GP in Zoetermeer, winning the bout against Swedish fighter Jorgen Kruth by extra round majority decision.