Cycling great Eddy Merckx said Tadej Pogacar had already written himself into the history books at just 24 after the Slovenian equaled the Belgian's achievement with his win in the grueling Tour of Flanders.

Pogacar on Sunday became the first Tour de France winner in almost half a century to also win the world's toughest one-day race contested over 19 cobbled hills and an epic 274km.

Merckx, who won both the Tour de France and the Giro d'Italia five times, told French sports daily L'Equipe he had greatly enjoyed watching Sunday's action-packed climax.

"That was an amazing race, the struggle between Pogacar and (outgoing champion) Mathieu van der Poel VP made it incredible," said Merckx, who won the Tour of Flanders in 1969 and 1975.

"The winner is quite simply out of the ordinary," said 77-year-old Merckx.

"What a rider this Pogacar is. I can never say it enough, he's so much more than just a champion. You have to consider the meaning of what he has achieved, this is no small thing."

Only two other riders had achieved the rare double before Sunday, Merckx and Louison Bobet, in the 1950s, which Merckx said "places his achievement in context".

Merckx pointed to the savvy shown by Pogacar to get the better of his rivals.

"The panache and audacity needed to achieve such an exploit has carved him a place in history. He is displaying a level of form rarely seen in cycling before him."

Merckx also said he liked Pogacar as a person.

"I met him once in Italy when the pair of us were invited by the same sponsor. He's a great guy, so easygoing, I was won over straight away."

Pogacar has taken the cycling world by storm since first emerging as a 20-year-old at the Tour of Spain where he won three stages in 2019.

The following summer he produced a dark horse run for the ages to take the Tour de France overall lead on the final day of racing aged just 21.

The UAE team rider then towered over a Covid-hit Tour de France in 2021, winning by a wide margin.

However, the risk-taking rider then persuaded his team to allow him to tackle the leading one-day races -- and the balancing act has produced mixed results.

While he won major races such as the Tour of Lombardy and Liege-Bastogne-Liege, his exploits perhaps robbed him of an edge in the 21-day Tour de France, where he slipped to second place in 2022.