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.