Roger Federer and Novak Djokovic have congratulated rival Rafael Nadal after the Spainard claimed his 21st grand slam victory with an epic five hour victory over second seed Daniil Medvedev at the Australian Open.

The 35-year-old now has one more major title than Federer and Djokovic, his long-time rivals in the so-called Big Three.

With the 2-6, 6-7 (5), 6-4, 6-4, 7-5 win, Nadal also became just the fourth man in history to win all four of the sport's major titles at least twice.

Roger Federer's Instagram post.

"What a match!" Federer wrote on Instagram. "To my friend and greatest rival Rafael Nadal. Heartfelt congratulations on becoming the first man to win 21 grand slam singles titles. A few months ago we were joking about both being on crutches. Amazing. Never underestimate a great champion.

"Your incredible work ethic, dedication and fighting spirit are an inspiration to me and countless others around the world. I am proud to share this era with you and honoured to play a role in pushing you to achieve more, as you have done for me for the past 18 years. I am sure you have more achievements ahead but for now enjoy this one."

Australian tennis legend and winner of 11 grand slams Rod Laver called the win 'Herculean'.

Nadal and Medvedev packed a lot of drama into the final that started Sunday night, was delayed for a while in the 84-minute second set when a protester jumped onto the court, and then finished early Monday morning.

"Good evening. No, good morning!" Nadal, looking at his watch, told the crowd at Rod Laver Arena when he finally got up for his acceptance speech at 1:30 a.m.

In the background, Rod Laver, the ageing Australian tennis great, was in the stands holding up his smartphone to capture the scenes. A woman nearby held up a sign that stated: "Rafa is the GOAT."

Rafael Nadal, right, of Spain is congratulated by Daniil Medvedev of Russia following his win in the men's singles final at the Australian Open tennis championships. Photo / AP

For now, in terms of men's major titles at least, Nadal is the Greatest Of All Time.

Nadal said it had been "one of the most emotional matches in my tennis career," and he praised Medvedev for the part he played in the 5-hour, 24-minute final. It was the second longest Australian Open final ever, after Nadal's loss to Djokovic in the 2012 decider that lasted 5:53.

His victory was even more remarkable considering Nadal flew to Australia with just two matches under his belt in the second half of 2021 because he was sidelined with a chronic foot injury that can be treated but not cured. He also overcame a bout of COVID-19.

"For me, it's just amazing. Being honest, one month and a half ago, I didn't know if I'd be able to play on the tour again," Nadal said. "Without a doubt, (it's) probably been one of the most emotional months in my tennis career.

Rafael Nadal of Spain celebrates his win over Daniil Medvedev of Russia in the men's singles final at the Australian Open tennis championships. Photo / AP

"The huge support I've received for the last three weeks will stay in my heart for the rest of my life."

Nadal won his first Australian Open title in 2009 and lost four other finals at Melbourne Park before his dramatic win over U.S. Open champion Medvedev. His conversion rate in major finals is now 21 out of 29. Federer and Djokovic each have 20 majors from 31 finals appearances.

- With AP