KAILUA-KONA, Hawaii — Craig Alexander of Australia and Chrissie Wellington of Britain are back to defend their titles against a deep field at the 31st annual Ironman World Championship.

Wellington will be going for her third straight win when 1,800 professional and amateur triathletes start the 140.6-mile endurance test on the Big Island on Saturday morning. Alexander is vying for a second straight crown.

Wellington set the Ironman world record in July, finishing in 8 hours, 31 minutes, 59 seconds at the Quelle Challenge in Roth, Germany.

"I love pushing my body to the limit," she said. "I'm stronger on the swim. I'm stronger on the bike. I'm stronger on the run. I know there's more inside of me."

Saturday's race begins with a 2.4-mile ocean swim in Kailua Bay, is followed by a 112-mile bike leg through sun-baked lava fields north along the Kohala Coast, and finishes with a 26.2-mile run to the finish line in Kailua Village.

Among Wellington's challengers are Sandra Wallenhorst of Germany, last year's third-place finisher, and Yvonne Van Vlerken of Netherlands, who held the world record for a year before Wellington lowered it by 13 minutes.

Also back this year is Michellie Jones of Australia, the 2006 Ironman world champion.

"Chrissie definitely has set the standard," Jones said. "I think the secret is you have to love what you do."

On the men's side, Alexander leads a field featuring five other former Ironman champions: Chris McCormack, Normann Stadler, Faris Al-Sultan, Tim DeBoom and Luc Van Lierde.

"There are six or seven guys who are going to be ultra-competitive," Alexander said. "The game plan is to get prepared, get fit, and race your own race. You have your best races here when you race your own race."

Every year, aspiring triathletes step up from shorter distances to test their mettle on the Big Island. This year, Terenzo Bozzone is one of them. The New Zealander won the half Ironman world title last year.

"It's a privilege just to be here," he said. "I'd love to be out front. You get more TV time that way."

Also making a debut in the Ironman is Mirinda Carfrae of Australia.

"This is the big brother of all races," said the 2007 half Ironman world champion. "I've known for a long time that ultimately Ironman would be where I end up, but your guess is as good as mine as to how it's going to go."

Lining up for the start will be 1,345 men and 508 women from 58 countries and 46 states ranging in age from 20 to 80, including 395 athletes making their first trip to Kailua-Kona.

Sister Madonna Buder of Washington is back to add to her legend at 79. She already holds the age group record for 75-79-year-olds, set in 2005.

Robert Southwell of Australia will try to become only the second 80-year-old to finish an Ironman.

The first-place man and woman each earn $110,000.


On the Net:

www.ironman.com