Rafael Nadal through to Australian Open final after epic five-set battle

The men's final at the Australian Open tennis will feature two players with a combined 31 grand slam titles.

Rafael Nadal and Roger Federer will go head to head after the Spaniard sealed an epic five-set victory over Grigor Dimitrov.

Nadal triumphed 6-3 5-7 7-6 (7/5) 6-7 (4/7) 6-4 after just short of five hours on Rod Laver Arena and will now face Federer, his greatest rival, in a mouth-watering showdown on Sunday.

Spain's Rafael Nadal celebrates after defeating Bulgaria's Grigor Dimitrov during their semifinal at the Australian Open tennis championships.

Dimitrov threatened to derail Melbourne's dream reunion by twice coming from behind to force a decider, but Nadal was relentless, powering his way through to his 21st major final and first since winning the French Open in 2014.

That he meets Federer there will be viewed as the perfect closing chapter to a throwback Australian Open, which now boasts four singles finalists aged 30 or older - a first for a grand slam in the Open era.

Venus Williams, 36, and her sister Serena, 35, will fight it out for the women's title on Saturday, in an exact replica of the finals bill at Wimbledon nine years ago.

Nadal then defeated Federer 9-7 in the fifth set, in what is widely considered the greatest match the sport has ever seen, but few would have predicted the pair would be meeting again for their ninth grand slam final, 34 major tournaments later.

Nadal will be chasing his 15th grand slam title to edge one closer to Federer, who stands on the brink of his 18th.

"It's a privilege," Nadal said on court afterwards. "It's a very special thing for both of us to be in the final of a major again and have the chance to compete against each other after a couple of years out with some problems.

"It was a moment we never thought we were ever going to have again, to be in the final in Australia, so we both feel very happy."

Nadal will also be bidding to win his second Australian Open title, which would see him become the first man in the Open era to win all four grand slam titles twice.

He was nearly undone here by Dimitrov, who came within a whisker of reaching his first major final and showed why many still consider him to be a multiple champion of the future.

The 25-year-old may well look back on three break points missed in the fifth set and wonder what might have been.