Alex de Minaur, for so long a "nearly man" of world tennis, has earned a major career breakthrough by defeating former world number one Daniil Medvedev in an epic affair at the Paris Masters.

The Sydneysider, who has built an excellent career while always seemingly coming up just short against the true elites of tennis, earned his first-ever victory over a top-five-ranked player on the 19th attempt with his thrilling 6-4, 2-6, 7-5 win over the Russian.

De Minaur had lost all his previous four encounters with the world number three including two matches in which he had won the first set — and it looked as if history would repeat itself on Wednesday on the Bercy hard courts as Medvedev fought back to take a 2-0 lead in the decider.

But de Minaur, ever the battler, regrouped, went on the offensive after what had been a remarkable cat-and-mouse affair studded by lengthy, probing rallies, and eventually looked mentally and physically stronger than Medvedev.

De Minaur came to the net 20 times in the final stanza and, ultimately, Medvedev, who had also been rattled in the first set after a grumble over a line call and getting whistled by the Parisian crowd, lost his nerve and finally cracked.

He served two double faults in the final game, the second of which gifted the 23-year-old Australian victory after a draining but wholly absorbing 2 hours and 46 minutes.

The Russian ended up smashing his racquet into the court amid a chorus of jeers from his Parisian audience who had already enjoyed baiting him during the contest — but he was quick to congratulate his never-say-die conqueror at the net.

The world number 25 de Minaur will take back his Australia number-one spot from Nick Kyrgios if he wins his next match, a last-16 contest against American Frances Tiafoe, the world number 21 who defeated rising Briton Jack Draper 6-3, 7-5.