Chelimo was selected in the Kenyan senior squad for the 10,000 m at the 1991 world championships, which took place in Tokyo. As Kenya's second runner he was assigned the task of being pacemaker to Moses Tanui. He was successful in dragging Tanui clear of his main rival, Morocco's Khalid Skah, and on the final lap he allowed Tanui to sprint clear to take the gold medal.