World-record holder David Rudisha of Kenya won a gun-to-tape victory on Tuesday to take the World 800m crown, banishing the heartbreak of his failure at the Berlin worlds in 2009.

The 22-year-old took the lead from the start and never looked in trouble, winning in 1 minute 43.91seconds, half-a-second quicker than Sudan's Abubaker Kaki (1:44.41), with Russia's Yuriy Borzakovskiy taking bronze (1:44.49).

The physically imposing Rudisha timed 51.33 seconds at the bell in front of a bunched pack and opened up with 200m to go, putting on an extra spurt in the home stretch to see him safely home.

The win spelled redemption for Rudisha, who was eliminated at the semifinal stage at the Berlin worlds two years ago, where inexperience and bad weather contributed to his poor showing.

Merritt dethroned

Grenada teenager Kirani James produced a fantastic final sprint and desperate lunge at the line to snatch the world 400m gold from defending champion LaShawn Merritt.

Reigning Olympic champion Merritt, returning to the world stage after a doping ban for testing positive for anabolic steroid DHEA, could only look on in horror as James pulled out his dip.

James, 18, clocked a personal best of 44.60sec, just three-hundredths of a second ahead of Merritt, with European champion Kevin Borlee of Belgium claiming bronze in 44.90sec.

Clement out

Earlier, defending World champion Kerron Clement slumped out of the 400m hurdles competition, finishing slowest out of all 24 runners in the semifinals.

Chernova takes gold

Russian Tatyana Chernova plucked the women's world heptathlon crown from Jessica Ennis after a woeful display of javelin throwing by the Briton.

After two gruelling days of the seven-discipline event, Chernova amassed 6,880 points, with Ennis taking silver (6,751pts) and Germany's Jennifer Oeser claiming bronze (6,572).

Isinbayeva crashes out

Yelena Isinbayeva pushed her gamesmanship one step too far and crashed out of the women's pole vault, a competition won by Brazil's Fabiana Murer.

Murer, who was fifth at the Berlin worlds in 2009, managed a best of 4.85m, with Germany's Martina Strutz taking silver (4.80m) and Russian Svetlana Feofanova claiming bronze (4.75).

Isinbayeva had to be content with a hugely disappointing sixth placing after just one successful vault. The 29-year-old, whose world record stands at 5.06m, came in at 4.65m and sailed over. Passing at 4.70m, she then bumped the bar off at 4.75, but rather than retrying at that height went up to 4.80.

Her first attempt at 4.80 was no better, Isinbayeva brushing the bar with her stomach as she screamed en route down to the mat.

A final attempt at the same height after those two failures saw the Russian not even get close to the bar and she was left to wave briefly to the crowd and exit the runway before pulling a blue cap hard down over her head.

Pistorius' dream over

Double amputee Oscar Pistorius saw his world 400m dream extinguished on Monday. Pistorius received a huge cheer from the South Korean crowd as he lined up to race, but could not find the pace he needed, timing 46.19sec to finish 22nd out of 24 runners in the semifinals.

The results:

Men: 400m: 1. Kirani James (Grn), 44.60s, 2. LaShawn Merritt (USA), 44.63, 3. Kevin Borlee (Bel), 44.90.

800m: 1. David Rudisha (Ken), 1:43.91, 2. Abubaker Kaki (Sud), 1:44.41, 3. Yuriy Borzakovskiy (Rus), 1:44.49. Discus: 1. Robert Harting (Ger), 68.97m, 2. Gerd Kanter (Est), 66.95, 3. Ehsan Hadadi (IRI), 66.08.

Women: Heptathlon: 1. Tatyana Chernova (Rus), 6,880 points, 2. Jessica Ennis (GBR), 6,751, 3. Jennifer Oeser (Ger), 6,572.

Pole vault: 1. Fabiana Murer (Bra), 4.85m, 2. Martina Strutz (Ger), 4.80, 3. Svetlana Feofanova (Rus) 4.75.

3000m steeplechase: 1. Yuliya Zaripova (Rus), 9:07.03, 2. Habiba Ghribi (Tun), 9:11.97, 3. Milcah Cheywa (Ken), 9:17.16.

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