World number three Naomi Osaka has withdrawn from the season-ending WTA Finals in Shenzhen due to a right shoulder injury.
The Japanese opened her campaign with a three-set victory over Petra Kvitova on Sunday but has deemed herself unfit to take part in her second Red Group match against Ash Barty on Tuesday.
She will be replaced by Kiki Bertens.
In a statement, Osaka said: “I’m disappointed to have to withdraw from the Finals.
“It has been a great event in Shenzhen, and it’s the biggest WTA event of the year. This is not how I wanted to end this tournament or my season. I look forward to getting healthy and hope to be back here in Shenzhen next year.”
Osaka ends her year on an 11-match unbeaten run having not tasted defeat since her US Open title defence ended at the hands of Belinda Bencic at the round of 16 stage in September.
Since then, the 22-year-old has registered title wins in Osaka and Beijing.