The venue change of the Ironman 70.3 world championship from Clearwater, Fla., to the outskirts of Las Vegas has everyone guessing who will rise to the top at this year’s race on Sept. 11.

The new Vegas course plays to Julie Dibens' strengths. Photo: Nils Nilsen

The venue change of the Ironman 70.3 world championship from Clearwater, Fla., to the outskirts of Las Vegas has everyone guessing who will rise to the top at this year’s race on Sept. 11. Expect the return of some familiar 70.3 series faces, but don’t count out some Ironman-focused pros who will race this year’s 70.3 worlds in the lead-up to Kona. With both defending champions Michael Raelert and Jodie Swallow not making the start we know we will have two new 70.3 champs. Read more about some of our favorites. Click here to view the complete start list.

Craig Alexander

Photo: John Segesta

Timing could be everything for two-time Ironman world champ Alexander, who races his best in the weeks leading up to Kona. He recently said his best race the past three years has been Muskoka 70.3 in Canada, which is four weeks before Kona. He’ll instead race Vegas this year, and the 38-year-old is fired up to reclaim the 70.3 world title, which he first won in 2006. “I’ve always felt my best distance is the half-Ironman,” said Alexander a few weeks after winning the 2011 Ironman Coeur d’Alene. “I’ve had winning streaks, and some of my best performances have been at that distance. So I want to go back [to the 70.3 world championship] and contest.”

Luke Bell

Bell recently began working with coach Matt Dixon, known for correcting unhealthy patterns of overtraining in many of his athletes—including Bell—and helping them achieve better results than ever before. The early outcome is auspicious: Bell raced three 70.3 races and an Ironman over the span of six weeks, finishing on the podium every time. The Aussie was runner-up at 70.3 St. Croix (where he fell short of the win by 16 seconds), overcame Chris Lieto on the run for the victory at Hawaii 70.3, and finished third at both 70.3 Kansas and Ironman Texas. Bell can swim and bike with the best; if he can nail the run he’ll be one to beat.

Joe Gambles

Photo: Nick Salazar

Gambles has made victory at this year’s 70.3 worlds his explicit goal for the 2011 season. At last year’s race in Clearwater, the Aussie led the race until the 5-mile mark on the run, when he was overtaken by eventual winner Michael Raelert and runner-up Filip Ospaly. Passed later by American Tim O’Donnell, Gambles held on for fourth place. We expect him to race at the front again this year, charging hard on the bike and run. With course records at Ironman 70.3 Lake Stevens and Vineman 70.3, Gambles has shown he’s a formidable competitor at the half-iron distance. He also captured his first iron-distance victory at the 2010 Ironman Wisconsin.

Maxim Kriat

Kriat, 26, is a specialist at the half-iron distance, racing eight 70.3 events last year and placing six times in the top six—including course record-breaking wins at 70.3 Augusta and 70.3 Mooseman. He’s carried that momentum into 2011, with early season wins at 70.3 St. Croix, where he had the fastest run split and edged out Luke Bell, and 70.3 Mooseman, where he clocked the fastest bike time. At both races the margin of victory over the runner-up was mere seconds, showing he can be a tough competitor when it comes down to the wire. The Ukrainian was runner-up at 70.3 Florida in June. If he can put together a perfect race, he has every chance of finishing the day atop the Vegas podium.

Chris Lieto

Photo: Paul Phillips

Like many of the athletes on this list Chris Lieto is using this race as a warm-up for next month’s Ironman World Championship. It would be a surprise if Lieto isn’t in the lead coming out of T2. As is the case in every race he enters, Lieto’s success will come down to how he does on the run. The hot and hilly bike course plays into Lieto’s strengths, meaning he may not need a monster half marathon to take the win.

Paul Matthews

A member of the Trek/K-Swiss team, the Aussie has dedicated himself to 70.3 racing. Matthews outraced Maxim Kriat for the win at last year’s 70.3 Syracuse. Known for his run strength, Matthews is having a breakout year with wins at Kansas 70.3 and the Washington D.C. Triathlon on back-to-back weekends. He’s got the short-course speed of a short-course triathlete that, paired with his long-course endurance, makes him a true threat in Vegas.

Filip Ospaly

A short-course specialist with an ITU racing background, Ospaly finished second to Michael Raelert at last year’s 70.3 world championship by a minute and a half. He is one of the few athletes who can keep pace with Raelert on the run. A three-time Olympian from the Czech Republic, Ospaly was the overall winner of last year’s Race to the Toyota Cup series, and won Ironman 70.3 Austria in 2010 and 2011. Ospaly ran away from the field to win the 2011 St. Anthony’s Triathlon in May, beating out the likes of Matty Reed, Cameron Dye and Andy Potts. If he’s among the leaders coming off the bike at this year’s 70.3 world championship, he’ll be tough to beat on the run.

Andy Potts

Photo: Nick Salazar

You can count on Potts being the early leader in every race he enters, from sprints to Ironman. As the sport’s fastest swimmer, the Colorado Springs-based Olympian always has a target on his back entering the bike leg. He’s on a hot streak this racing season, claiming wins at Ironman 70.3s in Oceanside and Florida, Ironman Cozumel, Escape from Alcatraz, Capital of Texas Triathlon and the Philadelphia Insurance Triathlon. Potts won this race in 2007 and placed sixth the following year. He’s been more focused on 70.3s in recent seasons, as it’s proven to be his racing “sweet spot.” We counted six races on Potts’ schedule between press time and race day, with half being 70.3 events.

Michael Weiss

The 30-year-old Olympian (2004) and Ironman champion (2010 St. George) is another versatile triathlete who excels at everything from Xterra off-road racing to Ironman. His 2011 season has included podium finishes at Oceanside 70.3, where he was third, and 70.3 Austria, where he was runner-up to Filip Ospaly. Known as the Austrian über-biker, he has the bike and run speed to pose a serious threat to race favorites Michael Raelert and Ospaly.

Leanda Cave

One of the most versatile women in the sport, Cave has proven she can perform at the top at 70.3s and Ironmans. She had a packed schedule after the 2010 Ironman World Championship (a few 70.3s and Ironman Arizona) and still managed to finish second at Clearwater. She’s one of few athletes who may be able to keep Julie Dibens within her sights on the swim and the bike. Like Magali Tisseyre, she is also now working with coach Siri Lindley.

Julie Dibens

Photo: Nils Nilsen

With her powerful swim/bike combo, Dibens will be tough to beat. The race course (hillier bike) and the timing (pre-Kona) suit her much better than Clearwater, and she’ll have fresher legs this year. She typically loses ground on the run, as evidenced at last year’s Rev3 Quassy and Ironman World Championship, but with a big-enough lead coming off the bike she can still hold on through the finish (as seen at June’s Ironman Coeur d’Alene). To win in Vegas, she needs to replicate her race from 2011 Rev3 Quassy, where she beat Mirinda Carfrae.

Heather Jackson

Jackson had her breakout race at 70.3 Oceanside this year where she nearly beat Mirinda Carfrae but finished second in a sprint. She’ll need to replicate that effort to make the podium in Vegas. A strong cyclist but weaker swimmer than Julie Dibens, she may struggle to catch Dibens in time to race her on the run.

Melanie McQuaid

Another Canadian, McQuaid is an Xterra world champ who’s turned her focus to the 70.3 distance and performed well. She’s one more cyclist who is well suited to the tough bike course in Vegas. She finished a disappointing 16th in Clearwater last year and will be looking to prove she can compete with the best at the half-Ironman distance.

Lesley Paterson

Paterson comes from an Xterra background and won’t be intimidated by the hilly Vegas course. The Scottish pro burst onto the 70.3 scene by finishing second at the 2010 Ironman 70.3 California race, nearly keeping pace with Mirinda Carfrae in the process. Now as a member of the Trek/K-Swiss team, Paterson filled her 2011 schedule with road triathlons, focusing mainly on the half-Ironman distance. Winner of this year’s 70.3 Mooseman, Paterson can bike and run with the best, but to win she’ll need a faster swim time than the 30:23 she posted at 2010 worlds, which ultimately led to a seventh-place finish.

Melissa Rollison

Australia’s Melissa Rollison first caught our attention by beating both Leanda Cave and Mirinda Carfrae at Vineman 70.3 in July, finishing out her 4:09 race with a blazing 1:16:28 half marathon. The former world-class runner is relatively new to triathlon—she just started last fall—so many will be watching to see if she’s the real deal in Vegas. She’s been training in Boulder for the last couple months, so she may now be more familiar with some of her competition than she was in July when she said she could barely tell her competitors apart from one another.

Magali Tisseyre

Photo: Paul Phillips

The Canadian is one of few athletes whose main focus is on this year’s Ironman 70.3 world championship race. After finishing on the podium the past two years in Clearwater, Tisseyre is excited to mix it up on a new course. She feels the tougher course, particularly on the bike, will suit her strengths: “I have a pride for hills on the bike,” she says. Tisseyre, who is now coached by Siri Lindley, Mirinda Carfrae’s coach, finished third at Wildflower and won 70.3 Rhode Island in July. She’s not shy about the fact that a win in Vegas is her ultimate goal this season. Tisseyre may not be a front-of-the-pack swimmer, but look for her to cycle and run her way to the front of the race.