Alexander Zverev made his debut as men's world number one with a defeat to Lorenzo Musetti in the second round of the Paris Masters on Wednesday, while Novak Djokovic also lost to miss out on a place in the ATP Finals.
German Zverev is out of the tournament after a 6-7 (5-7), 2-6 defeat, while Musetti advanced to the third round.
Zverev was competing for the first time since taking over the number one spot in the ATP rankings from Jannik Sinner. He will still finish the year at the top position.
"It's pretty shocking the level I was able to play in front of Sascha, who was serving really well, especially in the first set," Musetti said in his on-court interview.
Zverev was set to take control when he led 5-2 in the first-set tie-break. But Musetti raised his level and reeled off five consecutive points to snatch the opening set.
"It was really close. It could have gone both ways. The key was to stay there at 5-2. I played five great points in a row," Musetti added.
Seven-times Paris champion Djokovic was stunned by Australia's unheralded Rinky Hijikata 2-6, 6-3, 6-3.
Hijikata told Sky Sports: "It took a lot. I was getting outplayed in the first set and had to hang tough."
The 39-year-old Serbian had to reach the semi-finals to have a chance of making the season-ending championship in Turin starting on November 15. The tournament brings the eight best players on tour together.
Djokovic is the men's record Grand Slam champion with 24 titles, but he has not tasted major glory since 2023.
With former nemeses Roger Federer and Rafa Nadal now long retired, all tennis eyes will be on Djokovic's next move, although he has previously indicated he will play on next year.
