World number one Elena Rybakina advanced to the quarter-finals of the Ningbo Open after Polina Kudermetova retired from their match. Rybakina, who is 27 years old, held a 5-0 lead before the Uzbek player withdrew.
The defending champion will meet Katarzyna Kawa in the next stage of the tournament. In September, Rybakina won the US Open in New York, where she took the top world ranking from Aryna Sabalenka.
She previously missed the Wuhan Open due to a foot injury. Diana Shnaider, the 22-year-old world number 13, secured her place in the quarter-finals by defeating Alexandra Eala 7-5, 6-4.
Shnaider took the first set in just over 50 minutes and finished the match in 1 hour and 55 minutes. The winner will play Iva Jovic in the next round.
Iva Jovic, who is 18 years old, reached the quarter-finals after beating Jasmine Paolini 6-4, 6-3. Alexandra Eala, the 21-year-old world number 20, lost to Shnaider after previously beating Diane Parry in straight sets.
Eala made history in August by becoming the first player from the Philippines to win a WTA title.
