WUHAN, China (AFP) - Angelique Kerber survived a scare in her first match as world number one while French Open champion Garbine Muguruza crashed out in Wuhan on Tuesday (Sept 27).
The US and Australian Open champion, who had a bye in the first round, made a convincing start before missing two set points and allowing Kristina Mladenovic to take the first set in a tie break.
But the German then swept through the rest of the match, winning 6-7 (4/7), 6-1, 6-4 to set up a third-round meeting with two-time Wimbledon champion Petra Kvitova.
"I was trying to find my rhythm because I was not playing my best in the first set," top seed Kerber said after the match.
Meanwhile, Muguruza just couldn't master former world number one Jelena Jankovic, pushing her to a tie break in the second set but still coming up short at 6-4, 7-6 (7/2).
"I felt like I was in control of the match, but the last shot was not there. I made maybe too many mistakes against Jankovic," she told reporters.
The Spaniard bagged her first Grand Slam title at Roland Garros this year and rose to a career-high ranking of two, but the early round loss at Wuhan puts her qualification for the eight-player WTA Finals in Singapore in doubt.
Muguruza was the second seeded casualty of the day after last year's US Open finalist Roberta Vinci fell to Yaroslava Shvedova 7-5, 6-2 - her second defeat at the hands of the Kazakh this year.
Briton Johanna Konta had a tough battle to oust home crowd favourite Zhang Shuai in two sets, 6-3, 6-3, while world number four Agnieszka Radwanska romped into the third round when she downed Russia's Ekaterina Makarova.
Radwanska will next meet an in-form Caroline Wozniacki, who defeated qualifier Kateraina Siniakova 6-4, 6-4 on Tuesday, in the third round of the $2.6 million hardcourt event.
The former world number one beat Poland's Radwanska in the semi-finals of last week's Pan Pacific Open in Tokyo, en route to her first title of the year.
"We always (have) long battles against each other, especially on the slower surface (such) as here," Radwanska said of Wozniacki.
Kvitova, meanwhile, said she would be trying not to think about Kerber's new status as world number one, formalised when the rankings were updated after this month's US Open, when they play on Wednesday.
"(It) will be for the first time... that I will play her as a number one, which is a little bit different. But I think if I'm on the court, I don't really think about that," she told reporters.
Seven-time Grand Slam champion Venus Williams downed Yulia Putintseva of Kazakhstan 6-3, 6-2, and will next play fellow tour veteran 10th-ranked Svetlana Kuznetsova of Russia. The pair have not met on court since 2009.
American Madison Brengle fell to Kuznetsova 6-0, 6-4 in the second round, as eighth seed Madison Keys beat Caroline Garcia 6-3, 6-4.
Former Wimbledon quarter-finalist Barbora Strycova downed Japan's Misaki Doi, while Daria Kasatkina of Russia beat fellow qualifier American Louisa Chirico.