Craig Alexander (Aus)
Two-time Ironman champion won this year's Coeur D'alene Ironman in Idaho in a course record time of 8:19:48. The 38-year-old Australian was laid low for a month by a viral infection, missing Ironman Australia, so it was a particularly notable performance in his first race of the season. "I was prepared to give 100 percent of what I had but I didn't know what that was," he said afterwards. Plenty, as it turns out. Fourth last year (with a 2:41:59 run), he's in formidable form going into the World Championships.
Chris Lieto (US)
Lieto is one of the strongest cyclists on the circuit and it was his power that gave him the edge in this year's extremely windy Ironman Texas 70.3. He won Ironman Japan in 2006, Ironman Canada in 2005 and Ironman Wisconsin in 2002. The 39-year-old finished 11th last year in Kona and was second in 2009. He will need to pace himself better on the bike this time - he went too hard last year and paid the price.
Andreas Raelert (Ger)
The remarkable Raelert, who was second at Kona last year, broke the record for an Ironman-distance race at this year's Challenge Roth, which must have come as a surprise to Belgium's Marino Vanhoenacker at Ironman Austria, who had set a record only the week before. Raelert's time was 7:41:33. "This was the best performance of my life," he said afterwards. He and his brother, Michael, had planned to finish first and second at Kona this year, and win $1 million, courtesy of sponsors KSwiss, but Michael, who has been injured, has not qualified this year.
Rasmus Henning (Den)
Henning moved from Olympic-distance triathlon to Ironman in 2009 because he wanted to spend more time with his family (fewer races mean less travel). He made his mark quickly, winning Ironman China that year. Last year he won Challenge Roth, finishing a terrific race with a 2:39 marathon. He won this year's Timberman 70.3 in New Hampshire in 3:53:41.
Marino Vanhoenacker (Bel)
One of the quiet men in the sport, Vanhoenacker lets his results do the talking: at Ironman Austria this year he set a record time of 7:45:58. Andreas Raelert broke that record a week later, but that does not detract from an astonishing performance. It was Vanhoenacker's ninth Ironman victory. He knows he has what it takes to win in Hawaii.
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Find out more about the leading contenders for the women's Ironman World Championship title.