Wuhan (China): Reigning US Open champion Naomi Osaka of Japan withdrew from the Wuhan Open on Sunday due to a viral illness.
Osaka's decision came hours after losing the Pan Pacific Open final on Sunday to Karolina Pliskova of the Czech Republic 4-6, 4-6 ending the Japanese player's 10-match winning streak, reports Efe.
"I'm very sorry to have to withdraw from Wuhan. I look forward to playing in Wuhan next year," Osaka was quoted as saying on the WTA's website.
Osaka had earlier said she "felt really tired today" during her loss to Pliskova.
Wuhan Open co-director Fabrice Chouquet said he regretted the fact that Osaka was forced to withdraw after an "amazing few weeks" in which she became the first Japanese player to win a Grand Slam singles title.
Osaka, 20, prevailed in the US Open final on September 9 over US legend Serena Williams, who was penalized during the match by Portuguese umpire Carlos Ramos.
Ramos sanctioned Williams for receiving help in the form of a hand signal from her coach, Patrick Mouratoglou, as well as for breaking her racket against the court surface and verbally abusing the judge by calling him a "thief."
The Wuhan Open's co-director said Osaka is to be replaced by Polona Hercog of Slovenia, who lost in the qualifying to Puerto Rico's Monica Puig.
In the second round, Osaka, World No. 7, was due to take on China's Shuai Zhang, who defeated Samantha Stosur of Australia 6-2, 6-2.
Osaka is the latest player to pull out of the Wuhan Open following former World No. 1 Victoria Azarenka, who will also miss the tournament due to a viral illness.
Slovakia's Magdalena Rybarikova was forced to withdraw due to an upper respiratory illness.