DAEGU, SOUTH KOREA // Amantle Montsho won a thrilling 400 metres duel with Allyson Felix yesterday, securing Botswana's first world championships medal and denying the American a shot at a dream sprint double. Montsho dominated the race until Felix powered back into contention in the home straight, threatening to catch her on the line, but the Botswana runner stayed strong to win in a time of 49.56 secs, just 0.03 ahead of Felix. Felix, the three-time defending 200m world champion, was chasing a 200m-400m double in South Korea, but had previously described her quest as a "gruelling challenge". Russia's Anastasiya Kapachinskaya, who has the fastest time in the year in the 400m, took bronze in 50.24. "I'm so happy today to win my gold medal. I still can't believe it. I would like to thank all the athletes ... those who made me run faster, especially Felix, because she has good speed, so that made me run faster," Montsho, 28, said. "I'm sure that everybody is more happy than me at home. It's history in Botswana. Everybody behind me back home sent me some letters and comments, and that made me stronger. Elsewhere yesterday, Jason Richardson of the United States won the 110m hurdles crown when Dayron Robles was sensationally stripped of his title after crossing the line in first place. Robles won in 13.14 secs, edging out Richardson by just 0.02, but the Cuban's trailing right leg appeared to make contact with the left arm of China's Liu Xiang coming off the final hurdle. "Robles has been disqualified by the track referee under rule 163.2 for obstruction on the track," an IAAF official said, and later confirmed that Richardson was the winner, stating that an appeal from Cuba to have the disqualification overturned had been rejected. Liu was promoted to silver with Britain's Andy Turner taking bronze. Carmelita Jeter of the United States held off a strong field to claim gold in the women's 100m. Jeter, who won bronze at the last two world champs, was locked with defending champion Shelly-Ann Fraser-Pryce of Jamaica right through until the line. "It really means a lot," said Jeter. "My coach told me I needed a good start and I did just that." The American eventually prevailed in 10.90sec, but Fraser-Pryce missed out on a podium after being trumped by late surges from Jamaica's 2005 world champion Veronica Campbell-Brown (10.97sec) and Trinidad's Kelly-Ann Baptiste (10.98). Follow <strong>The National Sport </strong> on