ATP Finals 2025: Carlos Alcaraz & Jannik Sinner set for year-end number one battle in Turin

The war is about to start again.

Carlos Alcaraz emphasized this by using two emojis, one with a number one and one with a sword fight, in an Instagram post of him posing with Jannik Sinner after training ahead of Friday’s ATP Finals.

Whether Alcaraz or Sinner will finish the year as world number one is a matter of great curiosity at the end-of-season event to be held in Turin this week.

Finishing a long and grueling season as the best player on tour is a prestigious accolade that rewards players’ brilliance and consistency over the last 12 months.

Sinner’s defense of his title will be all the more remarkable as the 24-year-old Italian has been banned for three months and failed two doping tests.

Spaniard Alcaraz finally overtook his rival at the top of the rankings in September and won the final Grand Slam of 2025 in New York, ending Sinner’s 65-week run.

There are now two clear horse races heading into the final race of the season and the 22-year-old Alcaraz looks like the favorite to win the duel.

“If Carlos plays really well we have no chance, it doesn’t matter what my result is,” Sinner said.

BBC Sport analyzes each player’s permutations and who could potentially stop them. At the bottom of the page you can vote for who you think will triumph in Turin.