Sabalenka stunned by Bartunkova at China Open

World number two Aryna Sabalenka followed Elena Rybakina out of the door at the China Open as she fell to a surprise defeat by 34th-ranked Nikola Bartunkova.

It came a day after top seed Rybakina, who defeated Sabalenka in last month's US Open final and replaced the Belarusian at the top of the rankings, was knocked out by Armenian world number 118 Alina Charaeva.

Czech Bartunkova sprung another upset at the WTA 1,000 tournament and continued her breakthrough season with a 6-4 6-3 victory over Sabalenka.

"I focused on myself, to be calm. She's a legend, so I'm really happy that I won the match," said 20-year-old Bartunkova, who will face Austria's Sinja Kraus next.

This is the first time since 2015 that the top two seeds have failed to reach the round of 16 at the China Open.

Sabalenka has not won a title since completing the 'Sunshine Double' in March, when she triumphed at Indian Wells and the Miami Open.

It has been a mixed year for Sabalenka by her high standards. She will finish without a Grand Slam trophy for the first time since 2022 and has often struggled to control her frustrations on court.

Against Bartunkova, she failed to convert any of her five break points and threw her racquet after falling a break down early in the second set.

Wimbledon champion Linda Noskova, meanwhile, made breezy progress with a 56-minute 6-2 6-1 demolition of Switzerland's Viktorija Golubic.

Japanese 12th seed Naomi Osaka also advanced to the fourth round by converting her fifth match point to claim a 7-6 (7-4) 6-4 win over rising Czech star Sara Bejlek.

World number one Rybakina confirmed on Sunday that she has withdrawn from this month's Wuhan Open due to a foot injury.

The decision came less than 24 hours after the world number one's exit in China.

"I'm very sorry to the fans who were looking forward to seeing me play," Rybakina said on Instagram.

"I'll take some time to rest and recover. Thank you for your understanding and continued support."

The Wuhan Open is scheduled to take place from October 12 to 18.

At the Japan Open, Carlos Alcaraz reached the semi-finals after opponent Denis Shapovalov retired with an injury to his right thigh.

Alcaraz, the defending champion in Tokyo, saved a set point in the opening set and was leading 7-6 (7-3) 2-1 when the Canadian was forced to withdraw.

It is just Alcaraz's third event since returning from a wrist injury at last month's US Open, where he fell to Ben Shelton in the quarter-finals.

He will face fellow Spaniard Jaume Munar for a place in the final.