The world’s best ultrarunners are descending on Chamonix, France, in preparation for the Ultra-Trail du Mont-Blanc, the iconic 170K (106-mile) race around the Mont-Blanc massif that takes place September 1-3. With five previous champions entered, plus a host of eager UTMB vets and newcomers, the competition runs incredibly deep, on both the men’s and women’s sides.

No American male has ever won the UTMB, but U.S. women have claimed the title five times. Top American David Laney, who placed third in 2015, expects “a trail battle that none involved will ever forget.”

The Men

On a perfect day, any one of the elite men’s competitors could take home the victory.

The overwhelming favorite is Kilian Jornet, 29, of Spain, who has been virtually unbeatable over the last few years. In 2017 alone, Jornet has claimed victory at the Marathon du Mont Blanc, Sierre-Zinal and Hardrock 100, after a winter that saw him summit Mount Everest twice without supplemental oxygen. Jornet is also a three-time winner of UTMB (2008, 2009 and 2011). Alongside Jornet are Frenchmen Francoise D’Haene, 31, and Xavier Thevenard, 29, who are both two-time winners at UTMB, D’Haene in 2012 and 2014 and Thevenard in 2013 and 2015. Between them, the three hold seven of the last nine UTMB titles.

But, there are a handful of Americans who are poised to give the European trio a run for their money.

David Laney, 28, of Portland, Oregon finished third in 2015 and fourth in 2016. Sage Canaday, 31, of Boulder, Colorado had a no-choice DNF in 2015 when he fell and required stitches around the halfway mark. Canaday has a formidable speed range (he’s raced the U.S. Olympic Marathon Trials twice with a PR of 2:16) and started off 2017 with a third-place finish at the Ultra-Trail Hong Kong 100K. Tim Tollefson, 32, of Mammoth Lakes, California, is another American UTMB vet—he finished third in 2016, and second in the CCC in 2015. Most recently, he won the Ultra Trail Australia 100K and earned second at Speedgoat 50K (Canaday came third).

Zach Miller, 28, who manages and lives in the Barr Camp cabin on Pikes Peak in Manitou Springs, Colorado, won CCC (UTMB’s 100K little sister) in 2015 and has won both the North Face 50 (twice) and the Lake Sonoma 50. He returns to Chamonix this year for his second time racing the full UTMB (he finished sixth last year).

Related: Watch, Zach Miller Chases the UTMB Title

Dylan Bowman, 31, of Boulder, Colorado made it all the way to Chamonix in 2013 but was prevented from racing by a last-minute ankle injury. But he won the Istria 100 in Croatia back in April and finished fourth at Utah’s Speedgoat 50K in July. He has been training in the mountains of Colorado all summer, so he’s ready for the alpine terrain.

Jason Schlarb, 38, of Durango, Colorado, comes to UTMB eager to avenge an unexpected DNF at the Hardrock 100 earlier this summer. Schlarb, who won Hardrock in 2016 in a tie with Kilian Jornet, was expected to contend for the podium again in 2017 before a stomach virus forced him out in the race’s early miles. He will be looking to improve on a fourth-place finish at UTMB in 2014.

There are also plenty of newcomers who are hungry for the podium. Chief among them: Jim Walmsley, 27, of Flagstaff, Arizona, who will continue his quest for redemption after two heartbreaking races at Western States. He’s new to UTMB, as is 21-year-old Andrew Miller of Corvallis, Oregon, who won last year’s Western States after Walmsley’s wrong turn at mile 93. Miller also won the Georgia Death Race last year, but was a DNS for the 2017 Western States and has struggled with a lower-leg injury this summer.

Fastpacker and adventurer Andrew Skurka, 36, of Boulder, Colorado will also make his UTMB debut this year. He isn’t as widely known as many of his fellow competitors, but his resume is filled with podium finishes, including first place at Colorado’s Silverheels 100 and Indian Creek 50, and Wyoming’s Bighorn 100, all in the last year. He also just broke Anton Krupicka’s 2010 FKT on Colorado’s 27-mile Pawnee-Buchanan loop. He’s a pro at self-supporting and fueling, and thrives on hilly courses.

The Women

The women’s field is no less stacked: “awesome,” “badass” and “phenomenal” are a few words up-and-coming trail star Amanda Basham used to describe the group of ladies that will toe the line next weekend.

Forty-year-old Frenchwoman Caroline Chaverot won UTMB last year, and is fresh off a recent win at this year’s Hardrock (actually, she’s won her last seven ultras). Swiss runner Andrea Huser, 44, finished second at last year’s UTMB and seventh in 2014, and also won the UTMB’s 120K sister race TDS, in 2015. More recently, she won Portugal’s Madeira Island 115K and Switzerland’s Eiger Ultra Trail 110K and placed 10^th at Western States in June. The two put on quite a show at last year’s race, finishing within just seven minutes of one another.

Spanish runner Núria Picas has finished second at UTMB twice, in 2013 and 2014, and has twice won the competitive Transgrancanaria 125K in Spain.

But there are plenty of American women who could also make a run for the podium, including Basham. The 27-year-old Logan, Utah resident is a first-timer at UTMB, but she has won (among others) the Ultra Race of Champions and the Black Canyon 60K, and is fresh off a victory at the TransRockies Run (with teammate Keely Henninger, who will be a contender for this year’s CCC title).

Three former Western States 100 champs are also toeing the line. Kaci Lickteig, 31, has three top-six finishes at Western States including a victory in 2016. Magdalena Boulet, 43, was fifth at last year’s UTMB and has incredible range, from sub-17-minute 5Ks to a victory at Western States in 2015 (and a second-place finish in 2017). She’s one of the most consistent performers in this year’s field. Stephanie Howe Violett won Western States in 2014, and was eighth at UTMB in 2015.