Cuban Dayron Robles became another high-profile disqualification at the World Championships as he was stripped of his 110m hurdles gold medal.
Robles made contact with China's Liu Xiang and was disqualified after the Chinese appealed, handing Jason Richardson the gold and Liu the silver.
An appeal from the Cuban team was rejected and Britain's Andy Turner was awarded the bronze medal.
for a false start on Sunday.
Olympic champion and world record holder Robles brushed Liu's arm, causing him to trip on the final hurdle and finish in 13.27 seconds, behind Richardson, who clocked 13.16.
"Robles hit me twice, at the ninth hurdle he pulled at me but I'm sure it wasn't intentional," said Liu, who won 2004 Olympic gold and the 2007 world title.
"I lost my balance when I came to the 10th hurdle because of the bump. If not for the incident, I would have been the gold medallist."
European and Commonwealth champion Turner, who was removed from elite-level funding only two years ago after it was decided he was not capable of reaching major finals, struggled through the semi-final after a poor start.
He was initially placed fourth in 13.44 and said: "I didn't want to win a medal by default, but I have won a World Championship bronze medal and I'm over the moon with that, although I'm still disappointed with how I ran it."
Britain's William Sharman finished joint-fifth with Aries Merritt, complaining straight afterwards about clashing with the American over the first two hurdles.
"I was capable of getting a medal - it's really frustrating," Sharman said. "I'm an ambitious guy and when there are eight equal individuals on the start line I'm not eighth so I'm pretty gutted about that.
"It's been a hard year and I haven't been able to train for a large part due to injuries."
American David Oliver, the fastest 110m hurdler this year, was not involved in the controversy, having hit the second hurdle and finished in a distant 13.44 for fifth place, later upgraded to fourth following the disqualification.
Meanwhile, in the women's 400m final Amantle Montsho won Botswana's first ever medal at the World Championships.
Montsho held American Allyson Felix on the line to win in a time of 49.56 seconds, just 0.03 seconds ahead of Felix, with Russia's Anastasiya Kapachinskaya taking bronze in 50.24 and defending champion Sanya Richards-Ross seventh in 51.32.
Oscar Pistorius saw his historic appearance at the Championships come to an end
The 24-year-old South African, the first amputee athlete ever to compete in the competition and received finished last in his semi-final.
Pistorius, whose carbon fibre blades have provoked great debate over whether they give him an unfair advantage, clocked 46.19 seconds.
Defending champion LaShawn Merritt was the fastest in qualifying, timed in 44.76 seconds after recently returning from a doping ban.
Also through to Tuesday's final are Belgian twins Jonathan and Kevin Borlee, Grenadan pair Kirani James and Rondell Bartholomew, Tabarie Henry of the US Virgin Islands, Jamaica's Jermaine Gonzales and Nigeria-born Femi Ogunode of Qatar.
In the last final of the evening Carmelita Jeter raced to gold in the women's 100m.
She made a superb start and finished in 10.90 seconds, beating Jamaica's Veronica Campbell-Brown by 0.07 seconds with Trinidadian Kelly-Ann Baptiste third.
Koji Murofushi earned a surprise gold medal in the hammer with a throw of 81.24 metres on Monday to give Japan its first title of the Championships.
And in the pole vault Poland's Pawel Wojciechowski took gold following a leap of 5.90m.