Home favorite Li Na came from one set down to defeat compatriot Peng Shuai 4-6, 6-2, 7-6 (3) in a marathon battle which lasted two hours and 27 minutes, entering into the quarterfinals at the China Open on Thursday.
Three other quarterfinal spots in the WTA Premier Mandatory event were occupied by top two seeds Victoria Azarenka of Belarus and Maria Sharapova of Russia and fifth seed Angelique Kerber of Germany.
Seventh seed Li, the first Asian to win a Grand Slam title with her 2011 French Open championship, went into the third round with a 3-1 record against Peng, but she was made to work hard by her world No 49 opponent.
Peng broke in the eighth game to build a 5-3 lead in the final set, while Li fought back to level the score to 5-all before both sides held their services to force the match into the tie-breaker.
In the tie-breaker, the more experienced Li lighted up the night with her deadly returning power and iron-willed defence. Li took three points in a row after tied at 2-all and concluded the match when leading at 6-3 after Peng hit the ball into the net.
"Peng and I trained together and we are very familiar with each other's play style, but I basically controlled the rhythm on the court,"said Li.
The victory is a huge boost for Li, who is competing with Samantha Stosur, Marion Bartoli and Caroline Wozniacki for the final singles berth at the year-ending WTA championships.
Li is two matches away from becoming Beijing's first Chinese finalist, but World No 3 and defending champion Agnieszka Radwanska of Poland awaits in the quarterfinals.
Li met unexpected resistance from Peng as her 26-year old opponent broke in the fourth and sixth games in the opening set to establish a 5-2 lead. Though Li cut the deficit to 4-5 by breaking in the ninth game, she failed to save the break point at 40-advantage as she made a double fault to concede the first set 4-6.
Li found back her rhythm in the second set, taking four games in a row after 2-all to put the match into the final set.
World No 1 Azarenka defeated qualifier Elena Vesnina of Russia 6-3, 6-3 to set up a quarterfinal tie with Switzerland's Romina Oprandi, while Sharapova cruised past world No 90 Polona Hercog of Slovenia 6-0, 6-2 in just one hour and a half.
"I played really well in the beginning and got a little tense in the second set, but I felt like I really needed that challenge. It's nice to be in the quarter-final stage of this tournament," said Sharapova.
Sharapova will face Kerber, winner over former world number one Caroline Wozniacki of Denmark 6-1, 2-6, 6-4, in the last eight match.
In the ATP event, world No 165 Zhang Ze of China had a history-making 6-4, 3-6, 6-4 victory over fifth seed Richard Gasquet of France in men's singles second round, becoming the first Chinese player to advance into the third round in the event.
Other quarterfinalists include Mikhail Youzhny of Russia, Feliciano Lopez of Spain and Sam Querrey of the US.