Dayron Robles was on Monday sensationally stripped of his world 110m hurdles title for obstruction, American Jason Richardson handed gold after a nerve-wracking race. In another day of high drama at the world championships, just 24 hours after Jamaican sprint superstar Usain Bolt was disqualified for a false start, Robles made the fatal error of hitting rival Liu Xiang twice with his arm with the finish line in sight. The contact made Liu check his stride into the final hurdle, which he then stumbled off after hitting it with his trailing knee. The IAAF promptly disqualified Robles for obstruction, and rightly rejected a Cuban counter-appeal. Robles, the world record holder, was initially credited with having won the race that brought together the three fastest men of all time in the event (Robles, Liu and American David Oliver) for the first time. The Cuban shot out of the blocks and was immediately up on Oliver, but he faded midway through the race and had to rely on a quite amazing lift-off from his landing step on the final hurdle to edge out Richardson. But the contact had been made, and Robles was disqualified, Richardson taking gold, Liu silver and Britain's Andy Turner bronze. "I wish that under different circumstances he (Robles) could have kept his medal," said Richardson. "But rules are rules. I’m so happy to be a gold medallist. I'm the wedding crasher!" In front of a packed Daegu Stadium, there was also heartbreak for Oscar Pistorius, making history as the first amputee to compete at the world championships. The South African, who runs with carbon fibre prosthetic running blades, timed 46.19sec in his semi-final to finish 22nd out of 24 runners. "My goal was to make the semi-final and I did that," said Pistorius. "I'm a realist so for me to make the final, well I wasn't running close to those times. I never had." There was more disappointment in the women's 400m when American three-time 200m champion Allyson Felix, in her quest for a 200-400m double, could only finish with silver behind Amantle Montsho, winning a first ever world medal of any colour for Botswana. "I felt I gave my all but came up short," said Felix. "I'm happy that I still decided to go with the 400m. The final stretch was rough."Felix's teammate Carmelita Jeter held off a strong field to claim gold in the women's 100m at the world championships on Monday. Jeter, a bronze medallist 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 31-year-old 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 showings from Jamaica's 2005 world champion Veronica Campbell-Brown (10.97sec) and Trinidad's Kelly-Ann Baptiste (10.98). In the field, Valerie Adams of New Zealand retained her world shot title in emphatic fashion and there was a welcome return to form for Japan's 2004 Olympic champion Koji Murofushi in the men's hammer. Poland's Pawel Wojciechowski won the men's pole vault title with a best of 5.90 metres on countback from Cuban Lazaro Borges, Frenchman Renaud Lavillenie taking bronze (5.85m). British defending champion Jessica Ennis led the heptathlon after the first day, with 4,078 points after clocking 12.94sec for the 110m hurdles, 1.86m in the high jump, a personal best of 14.67m in the shot put and 23.27sec in the 200m. Russian Tatyana Chernova sat in second with 3,927pts, with American Hyleas Fountain in third on 2,093 after a dreadful shot put in which she could only finish 23rd out of the 28 competitors. "It's been a stressful day," said Ennis. "I knew it was going to be tough. It was hard. It was also hot. "I just need to believe that I can do it." The heptathletes on Tuesday round off their efforts with competition in the long jump, javelin and 800m.