BEIJING, Oct. 8 (Xinhua) -- World No. 1 Novak Djokovic finished with a lopsided win against Chinese player Zhang Ze, while US Open champion Flavia Pennetta failed to advance to the quarterfinals with a 6-3, 4-6, 3-6 loss to Russian Anastasia Pavlyuchenkova in China Open here on Thursday.
Djokovic didn't meet too much trouble on his way to the sixth title of the tournament, as he beat Zhang 6-2, 6-1 in just 55 minutes, claiming his 26th straight win here.
"I didn't give him (Zhang) many opportunities to really play his tennis because I was playing very quick," said Djokovic.
Djokovic set up a quarterfinal encounter with the sixth seed John Isner, who rallied past Australian John Millman 4-6, 7-6(5), 6-4.
Without much time to rest, Djokovic appeared on doubles' court with his younger brother Djordje Djokovic, but the brother duo lost to last year's Wimbledon champions Vasek Pospisil and Jack Sock 6-4, 6-1.
On her eighth appearance in Beijing, world No. 7 Pennetta upset Chinese wild card player Han Xinyun and Teliana Pereira in previous two rounds.
After trailing by 2-3 in the first set against Pavlyuchenkova, Pennetta took on a four-game winning streak to win at 6-3, before the Russian girl made a strong comeback.
Pavlyuchenkova won the second set 6-4 to force into the tiebreaker. After building a 3-0 lead in the tiebreaker, she maintained that lead to secure the 6-3 victory.
"We both played really well. I think she was really consistent, making not too many mistakes," Pennetta commented on her opponent's performance.
Before Pennetta's exit, top-seeded Simona Halep had withdrawn at the first round, with second seed Petra Kvitova falling at the same stage. Polish Agnieszka Radwanska became the highest-seeded girl currently in China Open, as the fourth seed advanced to last 8 on Wednesday.
Fifth-seeded Garbine Muguruza celebrated her 22-year-old birthday at China Open with a birthday cake from organizors, and more importantly, a 1-6, 6-2 and 6-1 win over Mirjana Lucic-Baroni and the ticket to Singapore for WTA Finals.
Bethanie Mattek-Sands and sixth-seeded Ana Ivanovic also advanced to women's singles last 8, while men's singles quarterfinals participants included Fabio Fognini and Pablo Cuevas.