BEIJING, China - No.8 seed Kiki Bertens strengthened her shot at a second straight WTA Finals appearance with a dramatic 7-6(6), 2-6, 6-3 win over Samsung Open champion Polona Hercog to reach the China Open quarterfinals.

Bertens, who remains in hot pursuit of a berth at the Shiseido WTA Finals Shenzhen, shook off a second set struggle to defeat the unseeded Hercog in two hours and 18 minutes as night fell on Lotus Court.

The Dutch star is in the midst of another career year after capturing a maiden Premier Mandatory title at the Mutua Madrid Open earlier this season, but has largely been left looking for that level since reaching the Palermo Ladies Open after Wimbledon, falling in the third round of the Dongfeng Motor Wuhan Open to eventual champion Aryna Sabalenka last week.

While Hercog has played the game's best tough throughout the season, she has been in search of a first Top 10 win since 2012, having lost her last 18 despite twice pushing Simona Halep to three sets at the Miami Open and Nature Valley International in Eastbourne.

Hercog nonetheless enjoyed a bright start to the Wednesday evening clash, thrice leading Bertens by a break - twice serving for the opening set - but the Dutch star broke back and forced a tie-break, roaring back from 2-5 down in the Sudden Death to turn the tables on the 28-year-old Slovenian.

Undaunted, Hercog took another 5-2 lead, this time in the second set, and made no mistake on the Bertens serve, breaking to level the match on her first opportunity.


The final set saw both women comfortably hold serve before Bertens stepped in what became an all-important fifth game, converting her the first break chance of the decider and ultimately riding that momentum to victory.

In all, she struck 15 winners to 29 unforced errors, and though Hercog struck more winners, she also made more errors, ending the match with a 23-42 differential. More efficient on break points, Bertens converted five of seven chances, while Hercog came away with five of 10.

Up next for the former World No.4 is either reigning WTA Finals champion Elina Svitolina or surging American Sofia Kenin, who won her third career title in Guangzhou just two weeks ago.