Germany's Alexander Zverev is set to finish the season as world No. 1 for the first time in his career after Carlos Alcaraz's surprise exit from the Shanghai Masters third round on Monday.
The career-first will cap a stellar season for the 29-year-old, the current world number two, after he won the French Open in June and the U.S. Open in September.
The French Open was his first-ever Grand Slam title.
"It's been a fantastic season for me winning in Paris and New York and knowing that I will finish the year on top of the rankings is just a dream come true," Zverev said in a statement shared by the ATP Tour website.
"So much work and effort have been put into achieving this goal, especially after coming back from the ankle injury," Zverev added.
He suffered a career-threatening ankle injury in his French Open semi-final in 2022.
Zverev will be the first German male player to finish his season as top-ranked in the world, and the oldest to lift the trophy, set to be presented in November, for the first time.
Germany's Angelique Kerber and Steffi Graf have both been the year-end number one women's tennis player.
Zverev's achievement comes in a year where the previous two players to hold the top ranking, Italy's Jannik Sinner and Spain's Alcaraz, have skipped months of competition due to injury.
Sinner, the current number one, has not competed since Wimbledon, where he beat Zverev in the final. He announced last week his season was over due to a knee injury.
Alcaraz, ranked third, was sidelined for months with a wrist injury from April until the U.S. Open.
Zverev, 6-foot-6 (1.98m), had been destined for the top from a young age, hailing from a tennis family where his mother and father both played the sport to a high level in the former Soviet Union.
But he plays in the shadow of domestic violence allegations made by two former partners, which he has strenuously denied.
The ATP Tour investigated one claim and found insufficient evidence to punish Zverev.
Another led to a 2023 penalty order and fine from a German court, which later dropped the case after a settlement was agreed in June of 2024, hours before he was due to play in the French Open semi-finals.