The era-shaping rivalry between Carlos Alcaraz and Jannik Sinner has injected fresh energy into men's tennis, 20-times Grand Slam champion Roger Federer said on Thursday as he looked forward to a blockbuster Australian Open showdown between the pair.

The duo dubbed "Sincaraz" have changed the landscape of the men's game by propelling it beyond the long-dominant "Big Three" of Federer, Rafa Nadal and Novak Djokovic, thrilling fans and sweeping nine of the last 10 Grand Slam titles between them.

They met in six finals overall last year, including at the French Open, where Alcaraz saved three match points to complete one of the sport's great comebacks in the longest Paris final at five hours and 29 minutes.

"That's why we're here," Federer said about the rivalry that fans and pundits expect to play out in the Australian Open final after title clashes in the other three majors.

"It's a great rivalry. They play incredible tennis and the French Open final was unreal. The game, not that it needed it, but it was great that we had it.

"For a moment, the sporting world stood still and watched what was going on in Paris in that epic fifth set. It could have ended sooner for Jannik and then all of a sudden it ended up in this crazy fashion. It was maybe one of the greatest matches.

"It's good we still live off that momentum and they backed it up by playing each other in all those other finals. Everybody else has tried to keep up while they're trying to pull away."

Career Slam vs Threepeat

The 22-year-old Alcaraz is chasing his first Australian Open title to become the youngest man to complete a career Grand Slam while the 24-year-old Sinner is targeting his third straight Melbourne Park crown to assert a dominance reminiscent of Djokovic's era.

"Their progression in the last few years is wonderful," said Federer, who lifted the last of his six Australian Open trophies in 2018.

"I've practised with both of them a little bit and they're incredible ball strikers. There's more to come, I hope they stay injury-free."

Federer said he hoped Alcaraz, who takes on 79th-ranked Australian Adam Walton in the first round, would achieve the career Grand Slam.

"He knows about it ... those things are tough. But his momentum will shift towards the first round and then it's a point-to-point mentality," Federer added.

"But at his young age, to be able to complete the career Grand Slam would be crazy, so let's see if he's able to do crazy this week. I hope he does, because that would be an unbelievably special moment for the game.

"But he has another 100-whatever players that say 'we don't agree with those plans', so they'll try everything to stop him."