(CNN)There may be a new tournament in men's tennis -- but the title will be decided by two of the game's longstanding legends.
New tournament, old rivals: Djokovic and Nadal to meet in inaugural ATP Cup final
Novak Djokovic and Rafael Nadal mustered all their experience to see Serbia and Spain through to the inaugural ATP Cup finals in Sydney, Australia.
The two tennis titans came through testing matches Saturday to once again inspire the hopes of their nations in the new team competition -- and set up their 55th meeting.
Djokovic muscled past Russia's Daniil Medvedev 6-1, 5-7, 6-4, in a match he described on ATPTour.com as "exciting, exhausting, joyful and dreadful all at once."
Athleticism is a big weapon for Djokovic and the 32-year-old needed to be at his physical best against the Russian world No.5, who faced off against Nadal in last year's U.S Open.
"It was a lot of rallies ... A very physical battle," added Djokovic.
With Dusan Lajovic already putting Serbia 1-0 up in their semi-final against Russia, victory for Djokovic sealed Serbia's place in the finals.
In the second tie, Nadal also had to call on his reserves as he came from a set down to see off Australia's Alex de Minaur 4-6, 7-5, 6-1.
"My energy was a little lower than usual," Nadal, who had lost to Belgian David Goffin on Friday, explained.
Nadal, the world No.1, couldn't get a break point against a fired up De Minaur but when one came along at the close of the second set, Nadal converted it and switched up his game, stepping into the court and putting pressure on the Australian.
"You need to have the mind clear and open to find solutions," Nadal added. "I needed to change something and that's what I did."
Nadal also backed up Roberto Bautista Agut's earlier victory over Nick Kyrgios to send Spain through to meet Serbia.
Lajovic and Bautista Agut will kick off play in Sunday's final, followed by Djokovic vs Nadal in their record 55th meeting. Djokovic leads Nadal 28-26 in the head-to-head and defeated the Spaniard in the 2019 Australian Open final.
A doubles match, which on paper features both Djokovic and Nadal, will decide who takes the title if the final is tied.
"Team competition is something that gets me going tremendously," says Djokovic. "I love it. All of the guys on the team are dear friends of mine, some of the best friends of my life."
Nadal added: "It's going to be a super-tough final against Serbia. We know Novak likes to play a lot here.