Tour de France: Prodigy Pogacar set to become youngest champ in 110 YEARS as he earns shock win in showdown of Slovenians (VIDEO)

Stunned newcomer Tadej Pogacar is poised to seal the Tour de France title after an astonishing turnaround against heavy favorite Primoz Roglic, destroying a 57-second deficit to leave his fellow Slovenian trailing in his wake.

Reigning Vuelta a Espana champion Roglic looked almost certain to make the most of his hefty advantage following a strong showing on Stage 20's time trial to La Planche des Belles Filles.

Despite the countrymen's form for engaging in nail-biting finales against each other this year, few had expected the experienced Roglic, who is nine years Pogacar's senior, to face a serious challenge in Saturday's mountain time trial.

Racing for UCI WorldTeam UAE Team Emirates, Pogacar made a mockery of predictions by establishing a 59-second lead by the end of the day.

Barring a freak turn of events, the prospect will be handed his first Tour de France trophy after the formality of the ride to Paris on Sunday.

Pogacar's ousting of Jumbo-Visma rider Roglic leaves him likely to become the youngest winner of the race for 110 years at the end of its processional climax.

He fired a warning signal when he pipped Roglic by 8.5 seconds in the Slovenian National Time Trial Championships earlier this year, avenging the reverse result the previous weekend, when Roglic won the national title for the first time by seeing off Pogacar in the final 1.2 miles.

Roglic had held the yellow jersey for 13 days but had little answer as Pogacar surged to a shock triumph that has all-but secured the first Grand Tour victory of his career.

He held his head in his hands and was mobbed by his thrilled team members as his win was announced after he had shared a hug with Roglic.

The result was his third stage victory of this year's tour and the fourth for his team.

Pogacar had dedicated his second win on the tour to Urska Zigart, his 23-year-old girlfriend who is a professional cyclist for UCI's women's team.

He also dedicated the win to Davide Formolo, his teammate who withdrew from the race after stage 10 following a crash that fractured his collarbone.

Shortly before his incredible finish, the official tour account called Pogacar's decision to change bike a "crucial strategic decision". "Hey...you've won the tour," it announced as he crossed the line.