About 575 triathletes, including 90 professionals, are scheduled to compete in the grueling Nissan Xterra World Championship on Sunday on Maui.

Nicolas Lebrun of Degne-les-Bains, France, and Melanie McQuaid, of Victoria, British Columbia, both 33, are back to defend their overall and women's titles, respectively.

The course, which starts and finishes at the Maui Prince Hotel in Makena, consists of a 1-mile roughwater swim at Maluaka Beach, a 20-mile mountain bike up the slopes of Haleakala and a 6.2-mile trail run through lava rock, forest trails and beach sand in South Maui.

Last year, Lebrun kept Eneko Llanos from winning his third consecutive world championship, finishing in 2 hours, 38 minutes, 19 seconds. Llanos, who also is entered this year, was second in 2:41:41. Llanos finished fifth in last Saturday's Ironman World Championship triathlon.

Lebrun captured this year's XTerra European Tour title.

Also entered this year are Seth Wealing, of Boulder, Colo., who won the 2006 XTerra U.S. Pro Point Series, and Brent McMahon, of Victoria, British Columbia, who finished second in the series consisting of six races.

McQuaid finished in 3:07:16, ahead of Sybille Matter (3:08:00) at last year's world championship.

Hawai'i's top finishers from last year also are back this year. Chad Seymour, of Honolulu, finished 16th overall. Ingrid Rolles of Honolulu was 12th among female finishers.

The event will air on "CBS Sports Spectacular" on Feb. 3.