Stefanos Tsitsipas has withdrawn from the ATP World Tour Finals in Turin due to a back injury.
The Greek sixth seed - who won the year-end championships in 2019 - suffered a straight-sets defeat in his opening encounter against Jannik Sinner in the Green group before taking on Holger Rune on Tuesday.
With the Dane 2-1 up in the first set, though, Tstisipas was forced to call it quits, and the 25-year-old revealed after retiring that he had first experienced pain in his back during the warm-up and feared that he would not be able to continue.
"For me, it's important to be fit and feel good with my back. The pain was very big," Tsitsipas told the media. "I've gone through pain during matches in the past, and I endured pain, but this was clearly too much to handle. I had to take the difficult decision to do what I did.
"I felt it at the second game of the match. I actually felt it in the warm-up with my serve. Warming up on my serve, I felt very irritated and lots of pain hitting me on my back. I kind of knew at that time that I might not be able to go all the way.
"My apologies to all the fans and the crowd that came to support me today and watch the match. I'm really gutted that I wasn't able to finish the match. It's a shame also not to give that spot to someone else to at least try and do something with it.
"My doctors and the countless visits that I had in the past few days suggested that I play, gave me the green light to go and try it for myself. Unfortunately, I felt terrible on the court. I did what I could do in the best possible way to be ready and fit for this match, but it didn't work out for me.
"I hate retiring from matches. I'm not the kind of person that likes leaving mid match. It kills me not to be able to finish this tournament, the one that I've prepped for for so long, made sure that I'm completely fit to perform at my best and show my capacities as a player."
With Tsitsipas bowing out of the ATP Finals, Rune has been credited with a straight-sets victory for his first year-end championships win, moving him top of the Green group standings before Novak Djokovic and Sinner clash on Tuesday evening.
Following the Greek's departure, alternates Hubert Hurkacz and Taylor Fritz took to the court for a one-set exhibition contest, while the Pole emerged triumphant in by six games to three.
Hurkacz has now replaced Tsitsipas in the Green group and will take on defending champion Djokovic in Thursday's round-robin contest, marking his first appearance at the ATP Finals since losing all three group matches in 2021.
