Headlining the race is three-time winner Daniela Ryf, who will be looking to add a fourth title to her already-impressive resume.

This weekend, the 2018 Ironman 70.3 World Championships will host one of the deepest pro women’s fields in the history of the race, with 46 strong contenders vying for the title and a share of the $250,000 pro prize purse.

Headlining the race is three-time winner Daniela Ryf, who will be looking to add a fourth title to her already-impressive resume. To do so, she’ll have to hold off a group of world-caliber contenders that include past world champions, Olympians, and some of the top athletes in the sport today.

Athletes will race a 1.2-mile swim at Kings Beach in Nelson Mandela Bay, bike a challenging 56-mile route along coastal roads in Port Elizabeth, and tackle a flat and fast run course on the shores of Hobie Beach. Last year saw the debut of the two-day racing format for the Ironman 70.3 World Championship, with men and women racing on separate days to ensure a clean, fair championship race for each field. The format will continue in 2018, the women’s pro race taking place on September 1, followed by the men’s pro race on Sept. 2. (Read the men’s pro preview here.)

Daniela Ryf (SUI)
Can anybody stop Daniela Ryf? In just about every race the three-time Ironman World and 70.3 champion enters, Ryf doesn’t just win—she dominates. Her record 3:57:54 finish at this year’s Ironman 70.3 Gdynia was more than 20 minutes ahead of the second-place finisher, former 70.3 and Ironman world champion Mirinda Carfrae. She’s a favorite to win once again, but will be racing with a target on her back.

Melissa Hauschildt (AUS)
Two-time 70.3 world champion Melissa Hauschildt is on one of her trademark winning streaks in 2018. After winning at the Tauranga Half Ironman in New Zealand, Hauschildt headed to Texas, where she bagged titles at both the 70.3 and full distances. In the latter, Hauschildt clocked an Ironman world record a time of 8:31:04. In June, she won Ironman 70.3 Elsinore. Could South Africa be her next victory in 2018?

Heather Wurtele (CAN)
Heather Wurtele pushed all her chips in on the 70.3 distance this year, eschewing the full distance in favor of preparing for the world championship race in South Africa. In addition to wins at Ironman 70.3 Campeche and Challenge Geraardsbergen, Wurtele has racked up a number of top-10 finishes in her build-up to this weekend’s event, where she’s sure to shine.

Emma Pallant (GBR)
Anyone ahead of Emma Pallant on the course should be running scared: the two-time World Duathlon Champion has a beastly bike-run combo. As the surprising runner-up at last year’s 70.3 World Championship race, Pallant could well find herself on the podium again in 2018.

Anne Haug (GER) 
Three-time Olympian Anne Haug is earning a reputation in 70.3 circles for running her way to the podium. Haug won her debut Ironman 70.3 race in Lanzarote last September, clocking a course-record 1:18:14 en route to her win. She’s only gotten faster since then, breaking several course records (including Ryf’s Ironman 70.3 Bahrain record) and setting a PR of 1:14:11 on her way to her 4:00:25 victory at this year’s Ironman 70.3 Dubai.

Jeanni Seymour (RSA) 
A home-country advantage could well work in Jeanni Seymour’s favor. The South African native moved to the U.S. seven years ago to pursue her triathlon ambitions in Boulder, and is excited to return to Nelson Mandela Bay to race for a world title on her home soil. She’s already proven she’s got the chops to do it, with eight career 70.3 wins under her belt. Can she make it nine?

Sarah True (USA) 
After 15 years of short-course racing, two-time Olympian Sarah True made the switch to 70.3 in 2017, and quickly made a name for herself with a win and three top-three finishes. She closed out her inaugural long-course season with a fourth-place finish at the 2017 Ironman 70.3 World Championship race. With another season of long-course racing experience under her belt, including a successful debut at the full Ironman experience, it will be exciting to see how True improves upon last year’s performance.

Helle Fredriksen (DEN)
Helle Fredriksen will be coming to South Africa with the confident swagger of a champion, thanks to her recent win at the 2018 ITU Long Distance World Championships. Frederiksen, who holds the world record for fastest time at the half-iron distance (3:55:50, Challenge Bahrain 2014), will also be using this weekend’s race as a stepping stone to her debut at the Ironman World Championship in Kona this October.

Lucy Charles (GBR) 
The first one to throw the gauntlet on race morning will be Lucy Charles. The stellar swimmer is all but untouchable in the water, and often enters T1 with a sizeable lead over her competition. But Charles is no one-trick pony: a second-place finish behind Ryf at her Ironman World Championship debut last year shows she’s got the skills to back it up on the bike and run.

Paula Findlay (CAN)
Paula Findlay doesn’t have much experience at the 70.3 distance, but don’t count her out. At the 2018 Ironman North American 70.3 Championship—only her third long-course race ever—Findlay took the win with a 4:15:53 over a stacked field that included Seymour, True, and Wurtele. She claimed to have not been firing on all cylinders that day, due to a winter stress fracture that set back her run training, which makes us excited to see what a healthy Findlay can do on the course this weekend.

See the complete women’s start list here.

The women’s pro race will take place on Saturday, Sept. 1, with live streaming available on the Ironman Now Facebook Page. The pro women kick off the day’s action at 7:30 a.m. local time (10:30 p.m. PDT Friday/1:30 a.m. EDT Saturday). Hosts of the commentary will be Ironman world champion Greg Welch, three-time Ironman champion Michael Lovato and three-time Ironman champion Dede Griesbauer.