The Spanish great looked dead and buried as the Russian world number two carved out a two-set lead but Nadal surged home for one of his mightiest comeback wins 2-6, 6-7 (5/7), 6-4, 6-4, 6-4 in 5hr 24min on Rod Laver Arena.
Nadal came out on top in the physical war of attrition to move ahead of era rivals Novak Djokovic and Roger Federer on the all-time list of men’s major winners.
Djokovic missed his chance to improve on his nine Australian Open wins when he was deported over vaccination issues on the eve of the tournament, while Federer is injured.
It was one of the 35-year-old Spanish warrior’s greatest title victories in his 29th Grand Slam final winning his second Australian Open, 13 years after his first in 2009.
Nadal also became only the fourth man to win each of the four Grand Slams twice and the third oldest man in the Open Era to win a Grand Slam title, behind Ken Rosewall and Federer.
The final went down to the bitter end with Nadal being broken as he served for the championship only for the Spaniard to break back.
On his second attempt to serve it out, Nadal powered to three match points to win amid chaotic scenes in his player’s box and the frenzied crowd.
It is the fourth time in his storied career that Nadal had clawed back to win from two sets down and the second time Nadal had denied Medvedev in a Grand Slam final, winning a five-set epic at the 2019 US Open.
It crowned an extraordinary effort from Nadal at the year’s opening major, having to modify his game to compensate for a degenerative bone disease in his left foot that ended his 2021 season last August.
He then caught Covid in December which, he said, made him “very sick”.
Medvedev had wrecked Djokovic’s calendar Grand Slam push and bid for a 21st title in New York four months ago and was aiming to do the same to Nadal in Melbourne.
Medvedev lost his second consecutive Australian Open final after falling in straight sets to Djokovic in last year’s final.
Nadal now leads Medvedev 4-1, with the Russian also losing to the Spanish lefty in his first major final at the 2019 US Open over five sets.