In one whirlwind week, Usain Bolt turned the biggest disappointment of his career into another golden show capped with a world record that even he didn’t think was within him.

After opening with a false start in 100 final last Sunday, Usain Bolt again produced the amasing in his closing race of the world championships – anchoring Jamaica to a world record in the 4x100-metre relay.

Fittingly, Jamaica’s yellow-green-and-black flag was the last one rising into the night over Daegu Stadium, and Bolt spread his giant arms wide to soak in the occasion with all his might.

“For me, it was just to go out there fast,” Bolt said. “We did just that.”

One day after winning gold in the 200, Bolt was devastating down the home stretch of the relay and threw his yellow-clad chest across the line for a time of 37.04 seconds – the only world record in nine days of competition.

There was no more of the performance anxiety that pushed him into a false start in the 100, only a sheer release of power as he coasted down the stretch for an overwhelming win over France and Saint Kitts and Nevis.

The United States was out of it by the last changeover, but no one could have gotten close to a Jamaican team anchored by Bolt.

Ahead of the race, Bolt was already slapping the “JAM” on his bib in pride, and in a season where he was far from his best, he came through with a world record he did not think was in him this season.

He got all the help he needed from his three teammates – a lightning start from Nesta Carter and a good handover to Michael Frater before Jamaica’s golden duo was up. Yohan Blake, the 100 champion in Bolt’s absence, powered through the final bend, with Bolt already getting his giant stride going before he took the baton.

Without the injured Asafa Powell, Bolt anchored the team for the first time in a major competition since he took the world by storm at the Beijing Olympics three years ago.

Running with the determination of a record beater, he gritted his teeth over the final metres, crossed the line and threw the glittering purple baton high in the air once he realised their three-year-old record of 37.10 was gone.

All through the year, Bolt had said that times were not his priority and he never came close to his record best – until yesterday.

Seconds later, the showman took over again. He started dancing to the delight of the 45,000 crowd at Daegu Stadium, which had to wait until the last second to finally see a world record.

On a final day of seven finals, one silver medal also stood out.

Caster Semenya failed to defend her 800 title, faltering late down the finishing straight to allow Mariya Savinova of Russia get the gold. Silver, however, was better than many expected as the South African showed glimpses of her powerful running that made her the dominating athlete over the distance two years ago, before a gender controversy sidelined her for a year.

“I achieved what I wanted, which was to get back to the podium,” the 20-year-old Semenya said. “I don’t talk about the past. I’m still young and I have to focus on the future.”

Allyson Felix added another gold to bring her collection of titles to a women’s record eight over four championships. The American ran the second leg of the winning 4x100 relay, one day after getting gold in the 4x400, too.

With Christian Taylor winning the triple jump, it left the United States at the top of medal standings with 12 gold and 25 overall.

Tatyana Lysenko won the women’s hammer throw, putting Russia in second place of the standings with nine gold and 19 medals overall.

Britain got some good news ahead of next year’s London Olympics, with Mo Farah holding off Bernard Lagat of the United States to win the men’s 5,000.

"The race came down to a sprint finish and I'm glad I took it," Farah said. "When you come so close to gold, you want that gold. You do everything you can."

Farah had to settle for the silver in the 10,000 last weekend when he was overtaken by Jeilan Ibrahim of Ethiopia on the final stretch.

He wasn't going to let that happen in the 5,000.

"Unfortunately, I wasn't aware of Ibrahim in the 10,000," Farah said. "I had to work everyone out and I knew it would come down to a sprint finish and I just made sure I had something left."

Farah won in 13 minutes, 23.36 seconds. Lagat was second, 0.28 seconds back. Imane Merga originally finished third but was later disqualified for stepping off the track, giving the bronze medal to Ethiopian teammate Dejen Gebremeskel, who finished in 13:23.92.

Farah started out slow in yesterday's race but moved up after 3,600 metres, closing the gap on leader Abera Kuma of Ethiopia.

Lagat, who won silver two years ago and was the 2007 champion, joined Farah in the lead after 4,000 meters.

With two laps to go, Farah moved into the lead by himself and looked to be in control until Lagat came outside of the two Ethiopians and made a late sprint with 80 meters remaining, almost catching Farah at the finish line.

"It turned out to be a good race for me," Lagat said. "I tried to put myself into a good position for the long kick but I got kind of blocked. When I got out, it was too late to get ahead."

After the race, Farah fell to his knees and kissed the track before doing a victory lap with the British flag draped over his shoulders.

The next big step for Farah will be representing his country at next year's London Olympics.

"I'm looking forward to it," Farah said. "To have an Olympics on your doorstep will be amazing. You can't doubt the field. You've just got to keep doing what you are doing and hopefully stay injury free."

Defending champion Kenenisa Bekele withdrew from the race after dropping out of the 10,000. Bekele had been injured for most of the past two years and did not look fit last Sunday.

Isiah Koech of Kenya, who is only 17, made an impressive debut at the worlds, finishing fourth in 13:24.95.

But it was Farah who became a long-distance star this week.

"I just want to enjoy this moment for now," Farah said. "I'll go home and celebrate with friends and family. I'm glad I made the choice to switch from football to athletics."

It was about the only middle and long distance race which went wrong for Kenya.

From the starting gun to yesterday’s last day, Kenya dominated. Yesterday morning, Abel Kirui led teammate Vincent Kipruto to yet another 1-2 finish in the men’s marathon.

The defending champion won by the biggest margin in championship history, and after finishing the race in 2:07:38, he had to wait 2:28 to welcome Kipruto in a sweaty embrace.

It left Kenya with seven gold and 17 medals overall for third place in the medal standings.

“This is history,” Kirui said. “It is also good for the country. It is good for my family. It is great.”