Stefanos Tsitsipas was forced to withdraw from the ATP Finals in Turin on Wednesday, citing an elbow injury, and he has spoken of the emotions he is going through as a result.
The Greek world number four having to pull out paved the way for Britain's Cameron Norrie to make his first appearance at the year-end tournament in his place as the second alternate.
Norrie, who capped a stunning breakthrough year by winning the Indian Wells title last month, lost out to Casper Ruud in Green Group later on Wednesday and will next face world number one Novak Djokovic on Friday.
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The 26-year-old Brit became the second alternate to have to rush to Turin after home favourite Jannik Sinner replaced his Italian compatriot Matteo Berrettini on Tuesday.
Rafael Nadal was ahead of Norrie in the race to Turin rankings but the Spaniard ended his season in August to deal with a foot injury.
"I've taken the very difficult decision to retire from the 2021 ATP World Tour Finals due to my elbow injury, which has been bothering me for a couple of weeks now," Tsitsipas explained in Turin.
"It's a very difficult decision from my side and I was working really hard this year to get to play the finals and be part of this amazing event, but unfortunately I won't be able to continue.

Stefanos Tsitsipas hat sein Auftaktmatch bei den ATP Finals verloren

Image credit: Getty Images

"I'll be travelling today to see a specialist regarding my elbow, who is going to help me get ready for the new season, the upcoming season in Australia and feel 100 per cent again ready to compete with my highest.
"I think it was important to take that decision and not continue playing with pain and giving the opportunity to someone else who is in better physical condition than I am to potentially maybe make the semi-finals this year.
"I'm not in a state to be out on the court and I much more prefer to give that opportunity to someone else.
I'm heartbroken and I really hope I can get back to playing at 100 per cent again and be in front of my fans and perform at my best.

Highlights: Rublev beats former champion Tsitsipas at ATP Finals

Tsitsipas was considered a fitness doubt in the lead up to the tournament after he was forced to withdraw from the Paris Masters with an elbow problem.
The Greek star decided not to respond to a question posed regarding his fitness in Turin after he suffered a defeat in his opening match against Andrey Rublev.
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