He won three medals at the ICF Canoe Slalom World Championships with a gold (C1 team: 1999) and two bronzes (C2 team: 2002, 2003). He also won a silver medal in the C2 team event at the 1996 European Championships in Augsburg. Mordaski also competed in two Summer Olympics, earning his best finish of sixth in the C2 event in Sydney in 2000.