The battle is about to recommence.
Carlos Alcaraz emphasised it by using two emojis – a number one and a sword fight – in an Instagram post of him posing with Jannik Sinner after their pre-ATP Finals practice on Friday.
Whether Alcaraz or Sinner will finish as the year-end world number one is a key point of interest at this week’s season-ending event in Turin.
Ending a long and gruelling season as the best player on the tour is a prestigious accolade, rewarding their brilliance and consistency over the previous 12 months.
Sinner retaining the title would be even more remarkable given the 24-year-old Italian did not play for three months, having been banned for failing two doping tests.
Spain’s Alcaraz finally usurped his rival at the top of the rankings in September, ending Sinner’s 65-week stint by winning the final Grand Slam of 2025 in New York.
Now the clear two-horse race goes to the last event of the season, with 22-year-old Alcaraz looking the favourite to win their duel.
“If Carlos plays really well there is no chance, it doesn’t matter what my result is,” said Sinner.
BBC Sport analyses the permutations for each player and who could potentially stop them. At the bottom of the page, you can vote for who you think will triumph in Turin.