Sapporo Half Marathon
He gained selection for the 2011 World Championships in Athletics and came fifth for Kenya in the men's 10,000 m. That year, Mathathi set a course record for the Great North Run half marathon, finishing in a time of 58 minutes 56 seconds. Two weeks later he also won the Great Edinburgh Run 10K in course record time. At the start of 2012 he finished second at the Chiba Cross Country meet. He won the 10,000 m at the Hyogo Relays with a world-leading time of 27:35.16 minutes, but said that he intended to miss the Olympics and focus on a marathon debut at the Fukuoka Marathon instead. He won the Gifu Half Marathon for a second time in May and won the Sapporo Half Marathon in July.