Jim Walmsley, Beth Pascall, Tom Evans and Camille Herron are among the top names entered for this year's UTMB.
All four are entered for the 170km feature race of the festival in Chamonix, which will run from August 22-28.
The highly favoured American Walmsley will be trying to win this event for the first time and has temporarily relocated to France for better acclimatisation.
Britain's Evans, a former winner of the CCC race at the UTMB, is running the flagship event for the first time and will be hoping for a place at the top.
Spain's 2019 winner Pau Capell is another expected to challenge. Three-time winner Xavier Thevenard will also be there as he continues his comeback from long-term illness.
Russia's Dmitriy Mityaev, China's Zhao Jiaju and New Zealand's Scott Hawker will be others to watch out for.
As far as other Brits are concerned, Andrew Symonds and Harry Jones, who have previously placed fifth and 15th respectively, are the main contenders.
Staying with the Brits, Derbyshire-based Pascall will be seeking to improve on her best ever placing of fourth. The 2021 Western States winner has also placed fifth in this race but had to drop out during last year's event.
American Herron has set multiple ultra world bests on the road but is yet to make her mark at the UTMB. If she competes, she is sure to be a contender.
France's Audrey Tanguy, who has twice won the TDS race at the UTMB, and Netherlands' Ragna Debats could also be in the mix.
Jasmin Paris, the winner outright of the Montane Spine Race three years ago, and Anna Troup are other Brits who are looking to challenge.
Britain's trail running world champion Jonathan Albon, who won the OCC race last time out, should be one of the favourites in the CCC event.
Last year's OCC winner, Blandine L'Hirondel of France, switches to the CCC this summer, with New Zealand's Ruth Croft sure to provide tough opposition. Britain's Holly Page will be hoping to improve on her ninth from 2019.
Britain's Robbie Simpson is due to return to the OCC, in which he was second last year.
The organisers of the UTMB announced they received 22,853 entry applications. Despite the pandemic still causing uncertainty around travel, this was the third highest total ever. They had almost twice as many applicants for the main race as there were places - a 95% over-subscription rate to be exact. A total of 106 nations were represented in those accepted, with France, Spain, Italy, United Kingdom and United States having the most runners in that order.
Main pic: Tom Evans (credit: Laurent Salino)