Fully recovered, he returned to the European cross country meets and won again at the Cinque Mulini and Itálica races. He qualified for the 2001 IAAF World Cross Country Championships and won his first major medal in the men's long race. Kamathi won the bronze medal (behind Mohammed Mourhit and Serhiy Lebid) and led a Kenyan team which included Paul Kosgei and Patrick Ivuti to the team gold medal. An even greater achievement awaited him at the 2001 World Championships in Athletics. He took on defending world champion Haile Gebrselassie in the 10,000 m and managed to beat both him and Olympic medallist Assefa Mezgebu to the line in the final lap, taking the world gold medal in the event. The victory, in which Kamathi sprinted from fourth to first in the final 200 metres, broke Haile's undefeated streak of 37 races.