Sanya Richards of the United States claimed her first individual world 400m title as Jamaica's Usain Bolt looked ahead to achieving a unique Olympic and world sprint double.

Having twice won 4x400m gold in both the Olympics and world championships, this was the 24-year-old Richards' first solo gold as she avenged her defeat at the Beijing Olympics to Britain's Christine Ohuruogu on Tuesday.

Richards clocked a season's best of 49 seconds to beat home Jamaica's Shericka Williams, who ran 49.32, while Russia's Antonina Krivoshapka took the bronze in 49.71.

Defending champion Ohuruogu failed to find her traditional finishing speed and finished fifth in a season's best time of 50.21sec.

For the Jamaican-born Richards it finally gave her a title to match her 400m dominance on the Grand Prix circuit in recent years and provided her first individual major title.

British woes were eased a little when Phillips Idowu won the men's triple jump gold, beating defending Olympic and world champion Nelson Evora of Portugal.

Idowu, the 30-year-old Olympic silver medalist, landed in the sand pit at 17.73 metres - the best in the world this season - while Evora (17.55) was second and Alexis Copello of Cuba (17.36) was third.

Earlier, Olympic champion and world record-holder Bolt breezed through to the 200m semi-finals and remains on course to claim a world sprint double after coasting through to the semi-finals.

"I am okay. I may have looked tired this morning because the 200m was earlier than the 100m," said Bolt, who competed in a t-shirt rather than his usual singlet.

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