Isinbayeva implodes again in pole vault

Yelena Isinbayeva extended her string of failures at major events on Tuesday, going under the pole vault bar on her final attempt while five other competitors were still looking for gold at the world championships in Daegu, South Korea.

As the Russian was packing up her bag, Fabiana Murer of Brazil added the outdoor world title to the indoor championship only one year before the London Olympics.

Murer set a South American record of 4.85 metres to beat Martina Strutz, who set a German record of 4.80. Svetlana Feofanova gave Russia bronze with a height of 4.75.

"I lost again. But it's OK and I'm optimistic for next year," Isinbayeva said. "The Olympic year is more important. I was just unlucky."

Imperial despite recent performances to back it up, the two-time Olympic champion got into the competition last when others were already fighting for survival at a height of 4.65 metres.

It turned out to be the only mark she would clear, only a slight improvement over her no-height performance at the world championships in Berlin two years ago, starting a spiral of decline. She took a one-year break after losing to Murer at last year's indoor championships, hoping to come back stronger in Daegu.

It didn't matter.

When she used to go into a huddle, covered by blankets or towels to concentrate, her competitors used to fail. Now, oblivious to the reclining former world champion, they went higher and higher, leaving the Russian behind.

After Isinbayeva first missed at 4.75 metres, her rivals kept scaling the bar, forcing her into two attempts at 4.80 to even have a shot at the title. She failed at that height as well.

It left her without a medal for three straight global championships after a run of seven straight golds in Olympics and world outdoor and indoor competitions.

"I will delete everything in my memory before I go to the Olympics," Isinbayeva said.

At the halfway mark in the competition, the United States leads the medal standings with four gold and eight overall, ahead of Kenya and Russia with three gold among their eight medals.

Chernova beats Ennis for heptathlon gold

Tatyana Chernova ended the reign of Jessica Ennis in the heptathlon, rallying to take gold from the defending champion.

Chernova made the difference in the javelin early in the day, when the Russian's season best throw of 52.95 metres contrasted sharply with Ennis' 39.95.

In the concluding 800, Chernova knew she could lose nine seconds to the Briton, but with a great finishing kick almost beat the hard-charging Ennis at the tape.

It left the Russian with a total of 6,880 points, compared to 6,751 for Ennis. Jennifer Oeser of Germany took bronze with 6,572.

"It was so easy for me. It was a great end of the year and will help me prepare for the Olympics with the sense that I am a winner," Chernova said. "It strengthened the spirit and, if I can win over Jessica here, it can give me confidence for the future."

Jessica Zelinka of London, Ont., finished ninth with 6,268 points, the best-ever Canadian finish in the seven-discipline event at a world championship.

"I have it in me to get on the podium I just need to put it all together in one consistent heptathlon," Zelinka said. "That is the most important thing I am taking away from this."

Ruky Abdulai of Coquitlam, B.C., was 13th with 6,212 points.

Over the past two years, Ennis won gold in the multi-event indoor and outdoor world championships and at the European championships. She was counting on another outstanding performance for a boost of confidence ahead of her home Olympics in London next year.

Instead, it was the 23-year-old Chernova who won her first major title.

"It was always going to be tough this year and will be tougher next year," Ennis said.

Russia's Zaripova takes steeplechase

Yuliya Zaripova of Russia won the women's steeplechase, finishing the 3,000-metre race in nine minutes 7.03 seconds.

Habiba Ghribi of Tunisia won silver in 9:11.97 and African champion Milcah Cheywa of Kenya took bronze in 9:17.16.

Ghribi, who became the first Tunisian woman to medal at the worlds, said she hoped her showing would also serve as a reward for those at home that are still coming to grips with the monthlong protests that left 78 dead and led to the downfall of longtime dictator Zine Abidine Ben Ali on Jan. 14. It also sparked protests across the Arab world.

"I was thinking as I was running of the people who suffered a lot during the revolution," Ghribi said. "My objective was to give a gift to the people of Tunisia. I hope that I brought a smile to all Tunisian people."

The 27-year-old Ghribi, who splits her time between Tunisia and France, said she had just arrived in her home country when the protests kicked off in December. She said the often violent clashes between police and protesters and the looting that followed disrupted her training, but she still persevered.

Often, she was forced to stay indoors.

"I still remember while I'm training in the stadium, there were fires everywhere as I was running," said Ghribi, who set a national record with her time of nine minutes, 11.97 seconds and improved on her sixth-place performance two years ago in Berlin.

But just before Ali was forced to flee the country, Ghribi said she made the decision to decamp to France where she and her family have a house so she could better concentrate on her preparations for the worlds. It was a difficult decision, she said, because she was forced to leave her parents and other relatives behind.

"Tunisia was the gate to the whole Arab revolution," she said. "I am proud of my country and proud of what is happening now all over the Arab world. But my heart is still hurting for those who sacrificed their lives during the revolution."

Cheruiyot coasts into 5,000 final

In early action, 10,000 champion Vivian Cheruiyot coasted in the 5,000 heats to qualify for a final where the defending champion can clinch a long-distance double.