Beijing, Beijing, China, 1 October 2014 | AFP/AAP

Sam Stosur has upset world No.8 Caroline Wozniacki to advance to the third round of the China Open in Beijing.

The Australian was the more composed as the two players battled in a tense second-set tie break, saving five set points against her Danish opponent to wrap up a 6-4 7-6(9) win on Wednesday.

Stosur, the 2011 US Open winner, has had a lean run in China lately, falling at the Guangzhou Open and in Wuhan in her opening matches.

Wozniacki was hoping to confirm her place at the season-ending WTA Finals with a deep run at the $US5.4 million ($A5.8 million) tournament in Beijing, but crashed out in her first match after receiving a first-round bye.

This is the furthest Stosur has ever advanced in Beijing; her previous best result at the China Open was a second-round finish in 2011.

Next up for the former world No.4 is Frenchwoman Alize Cornet, who routed American Lauren Davis for the loss of just three games.

Meanwhile, world No.3 Petra Kvitova opened her campaign to win a second consecutive tournament in commanding style.

Kvitova defeated home-crowd favourite Peng Shuai 6-4 6-2 in her first match since her victory at the Wuhan Open last Saturday, advancing in Beijing with the same confidence she showed at the earlier tournament.

Peng, who made the semi-finals at the US Open last month, took a 2-0 lead before the Wimbledon champion stormed back, winning 12 of the next 16 games and wrapping up the match in just 66 minutes.

Peng throughout the match had difficulty dealing with her left-handed opponent’s powerful serves.

The Czech player will now meet 16th seed Venus Williams for a tricky third-round match.

The third seed in Beijing has enjoyed a return to consistency in China after an underwhelming North American hardcourt swing.