In his first major outing on the world stage, Chambers attained a new personal best at the 1999 World Championships in Seville, registering a time of 9.97 s for third place in the 100 m final. This made the 21-year-old the youngest ever World Championships 100 m medallist. North Americans dominated the event as Maurice Greene and Bruny Surin took first and second place respectively, with record runs of 9.80 s and 9.84 s, respectively. The British sprint team Chambers, Gardener, Campbell and Marlon Devonish performed well in the 4×100 metres relay event as runners-up in a time of 37.73 s behind the US team led by Greene. World record holder Maurice Greene was hitting his peak, winning three gold medals in Seville. However, at 21 years old, Chambers had achieved more than Greene had at that age: Greene's best was 10.08 s in 1996 and he had never reached a major final.