Chambers ran a 100 m world junior record of 10.06 s in 1997 and became the youngest ever world medallist in the event at the 1999 World Championships, taking the bronze. On his Olympic début at the 2000 Sydney Olympics he was the best European performer in fourth place. He broke the 10-second barrier twice at the 2001 World Championships. In 2003 he received a two-year athletics ban after testing positive for THG, a banned performance-enhancing drug and was stripped of the 100 m European title and record he achieved in 2002.