As the 2025 ATP season accelerates toward its grand finale in Turin, the Nitto ATP Finals emerge not simply as a last hurrah, but as the ultimate decider as to who the best player on the planet truly is right now. Here stands the showdown: Carlos Alcaraz and Jannik Sinner, two modern superstars inheriting the throne abandoned by the “Big Four,” now striding into Italy with it all to play for. 

The court’s two current best have shone in 2025, sharing all four Grand Slams between them and contesting three of those four finals against each other. Sinner reigned supreme in Australia, beating Alexander Zverev to defend his crown, before Alcaraz struck back at Roland Garros, rallying to overturn a two-set deficit against his Italian adversary. At Wimbledon, the two did battle in the showpiece once more, with Sinner this time emerging with his maiden All England Club triumph. Then, in the Big Apple, Alcaraz ended Sinner’s hard-court dominance, winning by three sets to one. 

Online tennis betting sites think the pair’s storied rivalry is poised to continue well into next year. One can bet on tennis at Bovada, and the American betting giant currently makes both men the joint 6/4 favorite to win in Melbourne in January. But before the curtain can rise on the 2026 campaign, 2025 still needs to come to a close, and it will do so in Turin next month with the ATP Finals. But anyone thinking that Sinner and Alcaraz will simply breeze through the rest of the field ought to think again. 

Over the years, a slew of underdogs have reigned supreme in the end-of-year extravaganza, defying their lowly seeding to topple the best players on the planet to emerge victorious. Here are the three lowest-seeded winners in recent history. 

David Nalbandian

Picture this: Shanghai, Masters Cup, November 2005. The tennis season is already a grind; the Finals, a lesson in mental attrition. Eighth seed David Nalbandian was barely on the radar, a late entry sliding in as Andy Roddick’s replacement. He had zero titles all year, merely the memory of marathon comebacks—five sets against Lleyton Hewitt at the Australian Open, two-set deficits clawed back at Wimbledon—enough to mark him as tough, if not transcendent.

Numbers can be deceptive. Nalbandian arrived with a 43-19 record, not glitzy but resolute, the antithesis of Roger Federer’s imperial 35-match win streak. No one gave the Argentinian a prayer. But in the cauldron, something grave and magical stirred. The Argentine quietly moved through the group stage, picked off Nikolay Davydenko in the semis, and then faced Federer—a man at the height of his powers, collecting records like souvenirs.

Down two sets, Nalbandian played as if liberated. The world watched, barely believing as his silk-touch backhand began to find improbable angles, as fire entered his footwork. Federer faltered, then fought, but Nalbandian refused to wilt even as the tiebreaks oscillated. The final margin: 6-7(4), 6-7(11), 6-2, 6-1, 7-6(3). The performance was one for folklore—an eighth seed toppling the Tour’s Goliath, forever the lowest-ranked champion, and in many minds, the Finals’ greatest escape.

Novak Djokovic

Some legends win because they’re expected to. Others, like Novak Djokovic in 2022, do it when even belief flickers. The Serbian’s year was an exercise in chaos theory: visa drama kept him away from Melbourne and the US swing, his Top 5 streak snapped, his major prospects disfigured by headlines and politics. He landed in Turin as a seventh seed—a number his years of dominance would mock, if not for circumstance.

But Djokovic is Djokovic precisely because crisis is context, never fate. The metrics of his run? Peerless. Unbeaten in all five matches—Stefanos Tsitsipas, Andrey Rublev, Daniil Medvedev, Taylor Fritz, and Casper Ruud all cast aside, each match a cold demonstration of tennis IQ, resilience, and that staccato two-handed backhand. Not only did he beat Federer’s record with his seventh ATP Finals title, but at 35, he became the event’s oldest champion and, thanks to ATP’s new prize structure, its richest.

Grigor Dimitrov

For years, Grigor Dimitrov was tennis’s riddle: a Federer mimic, an artist seemingly exiled from substance. In 2017, everything changed. Armed with a newly sharpened fitness edge, a Cincinnati Masters title, and his best season ever, the unheralded Bulgarian arrived in London seeded sixth—talented, but everyone’s second choice.

In the Big Smoke’s neon-lit precincts, he was magisterial. The backhand was velvet; the movement balletic. He swept his group—wins over Dominic Thiem, David Goffin, and Pablo Carreño Busta. Semis: after a sluggish first set against Jack Sock, Dimitrov detonated, dropping just one game in the next two sets. The final: a rematch with Goffin, who had himself just stunned Federer in the semis and was himself riding a dream. 

This was no fairy-tale cruise—Dimitrov had to bury nerves, rescue himself from break points, tilt momentum back at the line. The finish: a 7-5, 4-6, 6-3 grind that crowned him undefeated and pushed him to World No. 3. He would never scale such heights again.