A season ruled by two, finished by one — Jannik Sinner triumphs over Alcaraz for the ATP Finals title.

TURIN, Italy — Carlos Alcaraz ends 2025 with two Grand Slams and the year-end world No. 1 ranking. Jannik Sinner ends it with two majors of his own, plus the ATP Tour Finals.

Sinner defended his title Sunday night with a 7-6(4), 7-5 win, to bring the curtain down on a season that confirmed that this duo’s only real rivals are each other.

Sinner ends 2025 with a 91 percent win-rate (58-6), compared to 89 percent (71-8) for Alcaraz, who can improve at the Davis Cup next week. Alcaraz ends it with a 4-2 advantage in their head-to-head, leading 10-6 overall with seven wins in their last nine meetings.

It is tempting to ask who had the better year, with Sinner having lost three months to an anti-doping suspension.

But individual accolades aside, the real story is that Sinner and Alcaraz are dominating the sport — as a pair. Their eight slams won in a row is not a record, because Roger Federer (8) and Rafael Nadal (3) won 11 consecutively from 2005 to 2007, while Novak Djokovic (5) and Nadal (4) won nine in a row between 2018 and 2020.

But when Djokovic and Nadal were dominating together, at least different players were winning the ATP Tour Finals. Alexander Zverev lifted the trophy in 2018, Stefanos Tsitsipas in 2019, and Daniil Medvedev in 2020.

Now the ATP’s flagship event is also the preserve of Sinner and Alcaraz, with the pair contesting Sunday’s final just as they have done the past three Grand Slams, which had never happened in one year before they did it over four months in 2025. One of Sinner and Alcaraz won every event in which they both entered this year. Now, they collectively hold the five biggest titles in the men’s game.

In this latest encounter between the Big Two of men’s tennis, Sinner won his 31st indoor hard-court match in a row. He has now won 10 ATP Tour Finals matches in a row, without dropping a set.

But like many of their matches, the epic French Open final in June the salient example, this was in part about their collective brilliance. Like so many duos before them, these two players elevate each other to even greater heights and ensure the other keeps somehow getting better.

Alcaraz is peerless on the tour when it comes to effective variety, so Sinner has worked specifically on that since losing the U.S. Open final to try to close the gap. It paid dividends here, with a couple of lobs helping to secure the opening-set tiebreak.

Sinner is the tour leader when it comes to efficiency, and so after losing the Wimbledon final, Alcaraz worked to add more of that to his game. The result was a U.S. Open title in which he lost just a single set — to Sinner in the final — and was broken only three times. The pair are even trying to learn the other’s native language, and at times on Sunday, Sinner, not always the most expressive, was indulging in Alcaraz’s trademark finger to the ear celebration. They are raising each other’s level in a number of ways.

“Hopefully you’ll be ready for next year, because I’ll be ready,” Alcaraz said in his on-court interview.

On Sunday night in Turin, the two players produced their usual highlight-reel tennis. Alcaraz slapped away a forehand winner off a meaty Sinner approach shot in the third game; Sinner rifled a forehand down the line with a split-second to prepare for it in the sixth. A backhand that painted the line in the next game drew a face from Alcaraz that was part respect, part disbelief.

Indoors is a more natural arena for Sinner, but Alcaraz went for him from the start on Sunday. He played with a bit less variety than usual, hitting 18.3 percent of his shots outside the core groundstrokes against a 12-month average of 24.6 percent.

Part of this was down to the conditions and the short nature of most of the rallies, the latter a reflection of how much Alcaraz has improved his serve, which reduces the number of long points he needs to play.

Alcaraz’s level in the first set was superb; the problem was his opponent’s otherworldly serving. Sinner hadn’t been broken all tournament and showed why here, making 61 percent of his first serves — a drop off from his other matches — but winning 85 percent of those points in the opening set. A marked contrast from his struggles in the U.S. Open final two months ago, when those figures were 48 and 69. He has adjusted his right elbow position to be deeper since then, by achieving greater rotation in his service motion.

Sinner’s coaches, Simone Vagnozzi and Dareen Cahill, spoke in a post-match news conference about the importance of improving his serve after those struggles in New York. Sinner said in his news conference that the variety and serve have “evolved in a positive way — especially the serving,” since then.

“From the back of the court, it’s been a bit more unpredictable,” he added. Sinner also said that he is a better player compared to a year ago when he was the world No. 1.

Jannik Sinner defended his title to extend his absurd indoor-hard-court record.Clive Brunskill / Getty Images

A first drop shot of the match helped Alcaraz to a set point on Sinner’s serve at 6-5, but the Italian saved it with a nerveless delivery that drew a missed return from his opponent. And then came Sinner’s own variety, which swung the tiebreak in his favour. Having just botched a drop shot to hand back the minibreak for 4-3, Sinner produced a brilliant lob off an Alcaraz drop shot and then repeated the trick to earn two set points at 6-4. A big first serve did the trick this time, and after more than 75 minutes, he was ahead.

Another significant moment came toward the end of the set when Alcaraz required a medical timeout because of a hamstring injury. He played down its significance in a news conference afterwards but it coincided with him playing more aggressively, apparently less willing to get drawn into lengthy baseline exchanges.

More variety helped Sinner change the momentum of the second set, when a disguised forehand drop shot secured him the break back for 3-3. He then pinched another break in the 12th game to claim a win that on another night might have gone the other way.

On a surface on which Alcaraz has sometimes struggled, and at an event where he had a 3-4 losing record before this year, he was dominant and played impeccable tennis for most of the week. He’s shown that he can absolutely live with Sinner indoors, despite how dominant the Italian is in these conditions against everyone else, and on this occasion, Sinner had to employ another Alcaraz staple to win: world-class defence.

Alcaraz has the highest steal score of any player in the past 12 months (the proportion of points won when defending), but Sinner won 38 percent of such points on Sunday, compared to 27 percent for his opponent. Alcaraz’s tour-leading average for the previous year is 38.4 percent.

Alcaraz’s outstanding performance in defeat here was in keeping with the fact that while Sinner was the winner on Sunday, this has been two years defined by a pair of players, rather than two individuals. Sinner and Alcaraz get better every time they face off, meaning that the real loser from their matches is the increasingly forlorn chasing pack, who cannot even hope to meet them in the finals of the biggest events.