Flora Duffy swaps her road cycle for a mountain bike as she goes for her fourth consecutive Xterra World Championship in Maui on Sunday.

Duffy has astonished her sport by the margin of her victories in the ITU World Triathlon Series, but her form on the Xterra circuit has been even more convincing.

Last year, she produced the fastest swim, bike and run and in the process beat 25 of the men’s elite field, finishing the one-mile swim, 20-mile bike and 6.5-mile run in 3hr 15min. Scotland’s Lesley Paterson, the winner in 2011 and 2012, finished second, ten minutes back.

Duffy’s focus this year has been on ITU racing, and on Sunday she will come up against a host of talented competitors who have been racing the international circuit all season.

The women’s championships have attracted a particularly strong field and two athletes stand out.

Paterson has been one of the most consistent Xterra athletes, having won it twice and finished second four times in her past seven attempts. The Scot has battled lyme disease and other issues over the past few years but the 37-year-old is known as a tough competitor and wants the crown back.

Laura Philipp, of Germany — better known as an Ironman 70.3 racer — has been the surprise package this year as she appeared at Xterra France, her only Xterra race to date, and took the title with the second-fastest swim, fastest bike and fastest run. In the process, she beat established Tour stars Brigitta Poor and Helena Karaskova by eight minutes.

Philipp finished third at the Ironman 70.3 world championship this year and won four other 70.3 races. She comes into this race with very impressive road credentials and the endurance qualities needed to succeed in this type of racing. Since the 70.3 Worlds, she has focused solely on her preparation for this race and may pose the biggest challenge yet to Duffy.

Others to watch will be American Susie Snyder, third last year, Karaskova, who took the European tour title in September after four wins, and Poor, who won six races in Europe this season, including the European Championships in Denmark. This will be her first appearance in Maui.

After a lot of rain, the course conditions are likely to be especially tough with practice on the bike course being cancelled earlier this week.

• You can follow the action on Sunday on http://www.xterramaui.com starting at 4pm Bermuda time.