Usain Bolt brought world-class pizzazz to the athletics world championships on Saturday where one Olympic champion ducked out without completing even a single pole vault and another was in tears after false starting in her 400 metres heat.

Bolt, the world's fastest man, left the rapidly emptying stadium all smiles after posturing his way through a simple 100 metres heat. His grin was matched by the joyful Kenyans who swept all six medals on offer on day one.

Britain's Christine Ohuruogu was left sobbing on a stairway in Daegu's cavernous arena as rivals tried to console her after she was disqualified.

"I false started, people false start all the time. I wasted all that hard work. I am broken, you can all see I am broken," the 400 metres Olympic champion told reporters.

"I have nothing else to say, I false started...I worked really hard," she added.

World and Olympic champion pole vaulter Steve Hooker was equally disappointed. Having declared himself fit but undercooked after injuries had delayed his start to the season, Hooker failed three attempts to clear 5.50 metres.

"I had no confidence in what I was doing out there. It's tough to try and get a good jump when you feel that way," the Australian told reporters.

"No excuse for what happened today, I would expect more of myself," he added.

While confidence was in short supply in some quarters, ebullient Jamaican Bolt exuded it as he gestured to the crowd, fashioning his hair with his hands and using his fingers as pretend guns to fire at television cameras.

He was never tested in his heat, easing up after 60 metres yet still finishing the fastest qualifier in 10.10 seconds, 0.02 ahead of young compatriot Yohan Blake.

"I feel great. My goal is to go out there and execute, I came out and I did what I wanted to. I got my great start and I'm happy with that.

"My focus is to go out there and win and show the world I am still the best...nobody has beaten me all season and nobody has broken my world record," he added.

Allyson Felix kicked off her campaign for 200m and 400m double gold in the heats of the 400 metres, and looked comfortable.

"It felt controlled. I just wanted to establish 150 and go from there," the American said.

"It was a little quicker than I would have hoped for but I was trying to make it as easy as possible. I feel good and am excited to finally get started," she added.

Policewoman Edna Kiplagat was left with a skinned knee but the broadest of smiles when she survived a late fall to lead a Kenyan sweep in the women's marathon.

Daegu's spectacular stadium set against a backdrop of mist-covered mountains came to life as heats kicked off the 13th championships, but it was on the streets of the South Korean city that the first gold was won.

Kiplagat, with her long, languid style, broke clear of compatriots Priscah Jeptoo and Sharon Cherop over the last two kilometres of the race to win her first world title in two hours 28 minutes 43 seconds.

"This is my first championship... I did not have any special strategy," the 31-year-old grinned. "I fell down at the... refreshment station - my teammate Cherop hit my leg by accident. I was afraid I had hurt myself but I am okay."

Saturday's only other medals event also resulted in a Kenyan clean sweep when Vivian Cheruiyot won gold in the women's 10,000 metres ahead of Sally Kipyego and Linet Masai.

Another Kenyan, Priscah Cherono, finished fourth, making it the first 1-2-3-4 sweep in a women's 10,000 metres at the world championships.

"It is great to win gold in my first championships race over 10,000 with a personal best," Cheruiyot said.

"We were inspired by the marathon girls and we wanted to achieve the same," she added.

Asian champion Mayookha Johny qualified for the women's long jump finals in the World Championships to become the only second Indian to do so after Anju Booby George.

Mayookha, who won gold in last month's Asian Championships in Japan [ Images ], leapt 6.53m in the qualification round, which she managed in her third effort to finish sixth in Group B but that was enough for her to make it to the finals to be held on Sunday.

Brazilian Maurren Maggi led the time sheet after Saturday's qualification round in 6.86m.

Mayookha, who had a personal best of 6.64m, emulates national record holder Anju Booby George who had won a bronze in the Paris World Championships in 2003.