Stefanos Tsitsipas and Dominic Thiem will vie for one of the most prestigious titles in tennis at the ATP Finals on Sunday, with the suggestion the sport's established order could finally be under threat.
For only the third time in 16 years the final of the season-ending tournament in London will not feature at least one of the 'big three'. In fact, this is the second time in the last three editions of the event.
While Rafael Nadal, Novak Djokovic and Roger Federer continue to be the dominant forces on the Grand Slam stage, those fighting to bridge the gap are making important strides.
Federer: Next Gen have proved their point
Federer, whose hopes of a record-extending seventh title at the ATP Finals were ended by Greek Tsitsipas in the semi-finals, admitted the next generation of talent are catching up with the old guard with more consistent displays.
Thiem, far from a young player at 26, has already beaten Federer and Djokovic this week in the round-robin stage to reach the showpiece to add further credence to the belief the gap may finally be closing ahead of next season.
"Does it feel like it might be the best year yet? Possibly," said Federer after his defeat against Tsitsipas.
"Then the only issue is that it seems like me, Novak, and Rafa are healthy, healthier than maybe in previous years, as well.
"So from that standpoint, I think they have proved their point this year by qualifying for the Finals, and also now Dominic showed again at these Finals, and winning five titles, beating all of us top guys.
"Definitely it's that next step they need, and seems like Dominic is in his absolute prime right now. Yeah, I would think so.
"But then I look at the list of who finished world number one, who has been world number one all these years, and it's just crazy that it's always one of us.
"But we are not getting any younger. So their chances increase not because we are getting worse but because they are getting better, I believe."
Tsitsipas breakthrough signals a changing of guard
Whether Tsitsipas wins the final or not on Sunday there can be no denying this has been a hugely impressive performance by the 21-year-old on his debut appearance.
He pushed year-end world No 1 Nadal all the way in his final round-robin match, having already secured qualification for the semi-finals, and then underlined his confidence and composure with a fearless performance against Federer.
It seemed only apt that it was the youngest player in the eight-man field to defeat the oldest and most successful player in the tournament.
Tsitsipas saved all but one of 12 break points he faced in the match, and triumph against Thiem - someone he has lost four times against in six meetings - would be the perfect tonic to end his season.
"I'm proud of myself, how hard I fought, how concentrated I stayed in the break points," said Tsitsipas, who was described "as hard as nails" by Federer.
"I didn't crack under pressure. I was very composed and very mature in my decisions."
Thiem aims to complete memorable week with aplomb
Thiem, twice a French Open runner-up, is arguably the standout player this week, even with the achievements of Tsitsipas on debut.
The Austrian had never progressed past the group stage of the event in his three previous visits but has overcome a challenging schedule - facing Federer and then Djokovic back to back - along with illness to finish top of his group.
Tsitsipas is a big admirer of Thiem and admitted his elder counterpart has "inspired me a lot to be a better version of myself". That's high praise for the world No 5, who has already won five tour-level titles this season.
Victory for Thiem would also follow hot on the heels of success for girlfriend Kristina Mladenovic, who inspired France to Fed Cup triumph last weekend.
"This is a big, big dream come true for me," Thiem said after victory against Zverev.
"It is one of the biggest and most prestigious tournaments of the whole year and I'm getting the chance to play the final. It is unreal to me and to beat the defending champion, a very good friend and unbelievable player - it is an unbelievable achievement."
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