Kilian Jornet is back to defend his title at the Sierre-Zinal race in Switzerland on Saturday, while Maude Mathys is among the favourites on the women's side.
Jornet, who has won here eight times, has chosen one of his favourite races - also one of the most prestigious mountain events in the world - in which to make his return to big-time trail racing after the pandemic hiatus.
The Spaniard, who set the race record at 2:25:35 two years ago, will be part of a strong field as the event returns to the calendar.
The relatively fast 31km course with 2200m of ascent starts at Sierre at 570m and then goes up to the highest point at Nava at 24km at 2424m. The last 7km is mainly downhill to Zinal at 1680m.
Jornet will face opposition from Eritrea's Petro Mamu and Mexico's Juan Carlos Carera, who was fourth in 2019.
Britain will have representation from current World Cup champion Andrew Douglas and Robbie Simpson, who has finished second here three times, and Jacob Adkin.
Switzerland's Marc Lauenstein, Remi Bonnet and Stephan Wenk, Italy's David Magnini, Henri Aymonod and Francesco Puppi and American Hayden Hawkes will be other contenders.
Switzerland's Mathys will defend her title amid tough competition from former world mountain running champion Lucy Wambui of Kenya, who has won here three times.
Also expected to figure highly will be Switzerland's Judith Wyder, France's Anaïs Sabrié and Blandine L'Hirondel, Britain's Charlotte Morgan, Czech Republic's Marcela Vasinova and Lucie Marsanov, Italy's Alice Gaggi and Ireland's Sarah Sarah McCormack.
The event also represents the fifth stage of the WMRA World Cup.
Picture: Kilian Jornet (credit: Corsa in Montagna)