Cuban Dayron Robles was stripped of his gold medal pending an inquiry after barging past China's Liu Xiang to win the 110 metres hurdles final at the world championships on Monday.

American Jason Richardson, who finished second after Liu stumbled over the final hurdle, was installed as world champion with the Chinese handed silver pending the investigation into the race, which might be re-run, according to the governing IAAF.

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Robles, the 24-year-old world record holder and Olympic champion, made contact with Liu at least twice on his way to crossing the line first in 13.14 seconds.

Liu lost tripped on the last hurdle, a rarity for the 2007 world champion, and was only able to finish third in 13.27 behind Richardson, who finished in 13.16.

"Robles hit me twice, at the ninth hurdle he pulled at me but I'm sure it wasn't intentional," Liu told reporters.

"I lost my balance when I came to the 10th hurdle because of the bump. If not for the incident, I would been the gold medallist."

The pair embraced after the race but the Chinese team later lodged a protest resulting in Robles being disqualified and Richardson being handed the gold. Britain's Andy Turner was awarded bronze.

"I wish that under different circumstances he could keep the medal but rules are rules," Richardson, 25, said.

"Anything can happen in track and field if you just do your best and stay in your name.

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"I am so thankful to be the gold medallist. I truly believe I can break Robles's world record (of 12.87 seconds)."

It was a disappointing end to the race for Liu, who was starting to return to his best form after three years of misery and injury since he limped out of the heats at the Beijing Olympics.

Robles, who has also had his fair share of injuries over the last couple of years, got away to a great start from lane five and raced to the lead over the first five hurdles.

Liu, next to him in lane six, was gaining ground all the time, though, and looked like surging past the Cuban until the contact was made, allowing Robles and Richardson to beat him to the line.

One man whose evening no investigation could improve was American David Oliver, the fastest man this year and with Liu and Robles one of the trio of quickest high hurdlers of all time in the final.

The 29-year-old hit the second hurdle and was never in the race, slumping home in fifth, later upgraded to fourth, in 13.44.

Carmelita Jeter of the United States powered home to win the women's 100 metres title.

Jeter clocked a time of 10.90 seconds with Jamaican Veronica Campbell-Brown second in 10.97. Kelly-Ann Baptiste of Trinidad and Tobago pipped defending champion Shelly-Ann Fraser-Pryce by 0.01 seconds for the bronze medal.

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Jeter, who took bronze in Berlin two years ago and in 2007, got out of the blocks well and powered home with Campbell-Brown pushing hard to catch her after a slow start.

The 31-year-old Jeter is the second fastest of all time over the 100 and came to South Korea in terrific form, which included a 10.70 to win the Prefontaine Classic in June.

Amantle Montsho held off Allyson Felix to win the women's 400 metres final, earning Botswana its first gold medal at the athletics World Championships.

Montsho raced across the line in a time of 49.56 seconds with Felix just three-hundreths of a second behind. Anastasiya Kapachinskaya won bronze for Russia.

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Montsho established an early lead on the blue Daegu track but Felix started to reel her in down the straight. The American was breathing down Montsho's neck as the pair crossed the line but came up just short.

Defending champion Sanya Richards-Ross, who barely squeezed into the final, never got going in lane one and finished seventh.

There was no Hollywood ending for double amputee Oscar Pistorius in the 400 metres at the World Championships on Monday, even if he crossed the line last in his heat to cheers louder than those for most gold medallists.

The South African's battle to overcome a series of legal and performance obstacles and become the first amputee to run at a major championships on his carbon-fibre prosthetic legs has made him a sentimental favourite around the world.

The 40,000 packed into the Daegu Stadium gave the "Blade Runner" a rousing welcome when he came out on to the track for the third and last semi-final of the evening, just as they had when he qualified through the heats on Sunday.

The 24-year-old needed to finish in the top four to have a chance of a place in the final but when he came around the final bend he was battling for last place with Demetrius Pinder of the Bahamas.

Pinder pulled away to leave Pistorius to cross the line at the back of the field in 46.19 seconds, more than a second outside his personal best of 45.07.

Despite finishing last, Pistorius, who had expected to struggle to reach the final, was certainly not disappointed with his second race at a major international championships.

"I worked extremely hard to get here," he said. "I'm happy with my performance tonight ... not as quick as I wanted to be but it's great to have this platform to run on and it's been an unbelievable experience. I'll be back for the relay."

Pistorius will be allowed to compete in the 4X400m relay for his country as long as he runs the opening leg to avoid endangering other athletes with the prosthetics.

The prosthetics replace the lower legs he had amputated when he was less than a year old because of a congenital condition.