Cycling's final 21-day race of the season, the Vuelta a España, gets underway in Burgos Saturday with three Olympic champions taking on the mountainous route bookended by individual time-trials.

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The race starts in a heatwave with the mercury set to tip 38C (100F) on the first of 21 stages.

Slovenia's two-time defending champion Primoz Roglic of Jumbo Visma won the Olympic time-trial gold in Tokyo two weeks ago, while last year's Vuelta runner-up Richard Carapaz of Ineos claimed the Olympic road race.

Tom Pidcock is also on the Ineos team for his first ever Grand Tour after winning mountain bike gold in Japan having earlier this season earned himself a reputation as one of the best road racers in the sport.

Pidcock and Carapaz start the 3,417km tour in the service of Colombian climber Egan Bernal, aiming to become the youngest man ever to win all thee Grand Tour after his 2019 Tour de France and 2021 Giro d'Italia in May.

"It is a great honour for us, the organisers, that Team Ineos has fielded such a selection of champions", said Vuelta general manager Javier Guillen.

"Carapaz is now an icon with his Olympic title. The mastery with which he won the road race has thrilled aficionados all over the world," Guillen said of Carapaz, who was second to Roglic by just 24sec in 2020.

Spain have a good chance of honours too, as Mikel Landa of the Bahrain team looks to confirm long held hopes following his win at the Tour of Burgos.

Other contenders over a race featuring nine summit finishes on the 76th edition are Britain's Hugh Carthy of EF and French climber Romain Bardet of DSM.

Course designers have made the Vuelta possibly the toughest race of the year with the key detail being the final day time-trial over 33km to Santiago de Compostela.

The finale puts pressure on the two favourites -- Roglic because of his late meltdown to lose the 2020 Tour de France, and Bernal because he is regarded as too light to do well in that kind of exercise.

The pair look equally matched in the mountains, though Bernal would be more accomplished technically for descents or avoiding falls.

Organisers have also added sprint point bonuses in ten of the stages plus time bonuses for the top three in every single stage other than the time-trials.

"We want to make it as exciting as we can," organisers said.

The strict Covid protocols that were applied in 2020 will again be in operation with the race boasting its own mobile testing centre.