Chinese ninth seed Li Na was untroubled in the third round of China Open and advanced into the quarter-finals here on Thursday.

Home favorite Li only needed 47 minutes to dispatch Germany's Angelique Kerber 6-2, 6-0. With the triumph, Li extended the record against her 22-year-old opponent to a perfect 3-0.

"She (Kerber) totally lost her form today, and seemed to give up after losing the first set," said Li, moving into the quarter-finals for the third time after 2004 and 2006. She reached the semifinals last year, but was stopped by the final champion Svetlana Kuznetsova of Russia.

As Asia's top-ranked player and the highest Chinese seed, Li didn't perform well in the opening game by double-faulting to lose service. But she soon rallied back, capitalizing on two service breaks in the second and fourth games to lead by 4-1.

Li converted on her first set point in the eighth game thanks to Kerber's double-fault. The world number 58 German committed three double-faults to present a first-set victory to Li.

The 28-year-old Li dominated the second set, using deep, heavy groundstrokes to pressure Kerber to be trapped by unforced errors. Li easily took six straight games to put a quick end to the match.

Li will face Anastasija Sevastova of Latvia in the quarter-finals, who was fortunately through the third round as her opponent Nadia Petrova of Russia, world number 17, quitted the match.