Jannik Sinner outlasted Carlos Alcaraz to defend his ATP Finals crown in Turin, stretching his dominant indoor hard-court win streak to 31 straight matches. It was the sixth final of the season between the two young superstars, and Sinner finally snagged just his second win over Alcaraz in that stretch. With that, their rivalry has become one of the most finely balanced in modern tennis: 16 matches, 3,302 total points, and a dead-even split at 1,651 each. And now, Serena Williams’ former coach is weighing in on why these two are miles ahead of the rest of the field.

Recently, Patrick Mouratoglou shared his thoughts on Instagram, noting, “Carlos ends the season as No. 1 in the world. It’s deserved for sure, but it could have been also Jannik. Those guys are so close. They won most of the titles when they played the tournaments.” And close is exactly the right word.

Carlos Alcaraz locked in the year-end No. 1 spot during the event, while Sinner (despite winning the tournament) fell just short of the ranking. The margin between Jannik Sinner and Alcaraz was thin: only a few hundred points. But what’s shocking is difference between their points, and the rest of the field’s.

And that’s exactly what Patrick Mouratoglou was referring to when he emphasized how far ahead Sincaraz was. The gap between Alcaraz and Sinner and the current No. 3, Alexander Zverev, is so massive that Mouratoglou pointed out, “the difference of points between them and Zverev is as big as a difference of points between Zverev and #1000 in the world, which is completely insane.”

The 55-year-old then wrapped up his analysis by highlighting how tight the year-end race really was. “It has to be a number 1. You know, it’s the end of the year. There has to be a world number one,” he said. And with margins this slim, he stressed that it genuinely could have gone either way. “It’s Carlos. Congrats to Carlos.” Indeed it was a fair conclusion after a season where both players pushed each other to unprecedented heights.

And as for the rivalry itself, Alcaraz currently holds the upper hand, leading 10-6 in their 16 matchups. But Sunday marked a first: it was the first time the two squared off at the ATP Finals. However, this season alone, Sinner and Alcaraz made history. They became the first duo in the Open Era to face each other in three Grand Slam finals in a single year. They also became the first pair ever to meet in three major finals and the ATP Finals title match in the same season since the event began in 1970.

But even with the gap narrowing at the very top, there’s still room to grow – on both sides. Despite Jannik Sinner being closer than ever to reclaiming the world No. 1 spot, his own coach recently admitted there are still “areas where he can improve.” 

Why Jannik Sinner needs to study the Big 3 playbook

Darren Cahill, who coaches Jannik Sinner alongside Simone Vagnozzi, broke down what’s been working so well in recent weeks. He explained that Sinner and Vagnozzi “did an incredible job” reorganizing the serve and finding a smoother rhythm that boosted his first-serve numbers. Cahill also emphasized that it wasn’t just mechanical changes, as it was about rebuilding confidence and consistency behind the shot.

He went on to explain that the progress wasn’t only about raising the first-serve percentage. “If we had just wanted to increase the percentage, we would have slowed down his serve,” Cahill said.

Cahill also pointed out why facing players like Jannik Sinner and Carlos Alcaraz is so demanding. He said they don’t “let you breathe,” returning everything for long stretches and then stepping up to the line to fire off quick, high-pressure service games, much like the tempo Roger Federer used in his prime. That nonstop intensity is something the team actively studies from the Big 3: Rafa’s discipline, Novak’s return game, and Roger’s unpredictability, to bring more pressure to every point.

And now, with Jannik Sinner already putting up elite numbers (six titles and a 57-6 record despite missing three months) those lessons only make him more dangerous. The final in Turin showed just how evenly matched he and Alcaraz are, with both pushing each other to the limit.

That said, with margins this razor-thin, who do you believe has the edge heading into next season? Jannik Sinner or Carlos Alcaraz?