Yelena Isinbayeva became the latest victim of a curious curse at the world athletics championships on Tuesday, while Grenadian Kirani James lit up the track in the 400 metres to become the third youngest ever world champion.

Russia's pole vault queen Isinbayeva turned in a miserable performance in front of 40,000 spectators at Daegu's stadium, but James, who turns 19 on Thursday, was sensational in chasing down champion LaShawn Merritt on the home straight.

James has only a handful of senior races to his credit and his exuberant victory will thrill compatriots back home in Grenada.

There was no cheer for Britain a year before London hosts the 2012 Olympic Games, though, as the biggest hope for gold on home soil, Jessica Ennis, lost her heptathlon title.

Isinbayeva graced the cover of Tuesday's official programme on day four -- and like the cover stars on each of the previous three days of competition, the Olympic champion and world record holder suffered a shock and ignominious exit.

Day one featured Olympic and defending world pole vault champion Steve Hooker who exited without completing one successful jump. Day two's cover showcased Usain Bolt and he was disqualified from the men's 100m final.

Monday was the turn of Cuba's Dayron Robles who was stripped of gold for bumping in the 110m hurdles.

Isinbayeva at least got off the ground, but her failure to clear 4.80 metres was a poor showing from one of athletics' genuine greats. Instead Brazil's Fabiana Murer took gold with a distinctly lukewarm 4.85m, way short of Isinbayeva's 5.06m world mark.

"I am very disappointed I lost again but it is okay... and I am optimistic for next year," said Isinbayeva who held the world title in 2005 and 2007 before losing it two years ago.

"I came here expecting to medal. I am going to jump higher and higher."

These gripping Daegu Games have so far been shaped by high drama and disqualifications -- notably world's fastest man Bolt and the burly Robles -- but finally athletic performance was the focus.

James did not disappoint, surging past American Merritt just before the line to claim victory in a personal best time of 44.60. Olympic champion Merritt, who has just returned from a 21-month ban for doping, had come round the final bend with what looked like a comfortable lead before being beaten by James's finish.

"It's a great feeling, but it's great just being here representing my country," James told reporters.

"I was just trying to relax and finish strong," he added.

James's coach Harvey Glance, a former Olympic sprint relay champion, paid tribute to the champion.

"He's a freak of nature," American Glance told Reuters. "At 18 he's the first to make a final and then he goes out and wins the 400 metres. He's destined for greatness."

Three poor javelin throws which never got beyond 40 metres left the athlete trailing Russia's Tatyana Chernova with only the 800 metres left and she was never going to beat Chernova by the nine seconds she needed to become the first Briton to retain a world title.

"It's a silver medal so I can't beat myself up too much but I obviously wanted that gold," said 25-year-old Ennis. "I haven't shed any tears yet but I might. After the javelin I knew I'd thrown it away."

One athlete you would bet the farm on in 800 metres, though, is Kenyan Rudisha.

The rangy Masai simply ran from the front and nobody could catch him, winning in a time of 1:43.91 ahead of Abubaker Kaki of Sudan.

"I am very happy," said Rudisha who is unbeaten over 800 metres since the 2009 worlds.

"Having the world title is very important to me, more important that the word record. The title will remain with you for the rest of your life but the record can be broken," she added.