The first competitors are likely to finish between 11am and noon at the Lake Hawea Hotel.
Floortje Draisma (34) is no stranger to the 125km Round Lake Hawea mountain bike race, having competed in 2008 and 2010, when she filled sixth and third places respectively.
Today, Draisma will be gunning for a top-three result but is conscious she will have to do a sub-6hr ride if she is to catch her friend and four-times champion Kath Kelly, of Dunedin.
Draisma's recent second place in the Motatapu race in March, just 4min behind top-ranked New Zealand mountain biker Kate Flukers, has got people talking about the speedy Dutch mother of two who made Wanaka her home many years ago.
Race organiser Danielle Nicholson says Draisma is a "hardened athlete" who could disrupt Kelly's hopes of a fifth consecutive title.
Draisma admits she has a competitive spirit and would be giving the race her all.
"All respect to Kath. It's her race. She owns it. But I will look forward to it," Draisma said of the pending showdown.
Kelly's best time on the course was in 2008, when she completed it in 5hr 26 min.
Last year she won in 5hr 52min.
Also racing again this year is Kim Hamer-Hurst, who was second last year.
Draisma does not have a specific time goal in mind, because unexpected things can happen during off-road courses.
"I would like to be realistic but I would like to be under six hours. But you don't know what the landscape is going to be like on the day," she said.
Draisma is a seasoned multisport campaigner but did not compete in the Contact Epic in 2009, because she had just given birth to her son Liam. Last year she was overseas.
In her two previous outings on the gruelling off-road course, Draisma has trailed Kelly by about half an hour, although in 2010, she was held up by mechanical problems.
The delay, in cold, wet weather, also meant she finished in a near-hypothermic condition.
Draisma said she had learned her lessons from 2010 and did not want to be caught out by cold weather again.
"I can't wait. I am so excited. It is beautiful, especially this time of the year. And it looks like we will have good weather. I'm checking it out all the time," she said.
In the men's race, defending champion Dougal Allan, of Wanaka, can expect a tough, fast race against 2009 champion Brent Miller, of Christchurch, and 2010 champion Tim Wilding, of Wellington.
Allan clocked 4hr 43min over 125km last year.
Miller and Wilding are both capable of sub-5hr rides and will be hard on his heels.
Dunedin's Marcus Roy (2008 champion) holds the course record of 4hr 44min but is not racing.
Meanwhile, a "die-hard" local trio of Andrew McLeod, Blair Coupe and David Drake have obtained permission to go one better and trial two laps around Lake Hawea (250km), starting at 4am.
While they are not in the 125km race, if they complete at least one lap, they will retain their membership of the Last Man Standing club of about 40 competitors who have done every event since 2008.
"These athletes are local lads we know have the cycling ability and safety know-how to complete this ultra-endurance challenge. As for whether it will be opened up as a competitive leg in the future, we will see what they encounter en route. The true challenges are never visible until the day," Nicholson said.
The 125km Contact Epic starts at 7am on the Lake Hawea dam. The sister race, the 95km Contact Classic starts at 7am at Kidds Bush.
The first competitors are likely to finish between 11am and noon at the Lake Hawea Hotel.
