Spain's Garbine Muguruza moved to the brink of the WTA Finals last four with a 6-4, 6-4 win over Angelique Kerber on Wednesday after Petra Kvitova opened her account with a 7-5, 7-5 victory over fellow Czech Lucie Safarova.
Muguruza (2-0) came into the tournament on the back of her first premier level tournament win in Beijing at the start of the month and backed up her impressive opening round-robin win over Safarova with another straight sets victory over Kerber.
Kvitova (1-1), Kerber (1-1) and Safarova (0-2) can all still advance to the last four from the 'White Group' with one round of matches to play but Muguruza is in prime position to advance as the winner of the four-player pool in Singapore.
"Every time I step on the court against Angelique it seems to be a tough match so I knew I had to be at my best today to secure the victory," Muguruza said in a courtside interview after improving to 4-3 against the German.
The 22-year-old Muguruza started the contest full of positive intent, immediately finding the corners and licking the paint with her powerful ground strokes as she broke in the first game before Kerber had a chance to settle.
Slowly but surely, the German worked her way back into the set, breaking back in the fourth game through sheer determination and a tenacious defence as the pair fought tooth and nail to gain the ascendancy.
At 4-4, the Spaniard increased her intensity levels a notch and quickly forged three break points, edging ahead on the second of them and closing out the set with a blistering serve in the next game that Kerber sent sailing over the baseline.
Muguruza, who started the season ranked outside the top 20, continued to apply pressure at the start of the second as Kerber hung on by her fingernails, until the Spaniard finally converted her sixth break point of the set to edge 3-2 ahead.
Kerber refused to buckle, however, and broke back against the run of play in the eighth game before Muguruza wrestled back control in what had become a baseline slugfest, then closed out the contest as her demoralised opponent wilted under a barrage of booming forehands.
Earlier, Kvitova got her WTA Finals campaign back on track with a hard fought 7-5, 7-5 victory over Czech compatriot and Fed Cup team mate Lucie Safarova to record her first win of this year's elite eight-woman event on Wednesday.
Both women had lost their 'White Group' openers on Monday so were desperate to pick up a much-needed win and it was the double Wimbledon champion who made the most of her opportunities on the key points to help her emerge victorious
The powerful left-handers took to court in identical outfits and were also almost impossible to separate on the scoreboard, with each player racing through their service games in a tight first set high on winners and low on unforced errors.
A pair of huge serves put the double Wimbledon champion back in front and the set appeared destined for a tiebreak when Safarova led 40-15, but the French Open finalist wobbled and Kvitova pounced, wrapping up the opener with a big forehand.
Safarova shrugged off the disappointment by racing out of the blocks in the second, breaking twice to storm 3-0 clear before the world number five rallied behind her formidable forehand to quickly erase the deficit.
Kvitova had seized the momentum and was threatening to run away with the contest when she held two break points to forge 5-3 ahead before Safarova held firm through a mixture of guts and guile to drag it back to 4-4.
Both players were now playing their best tennis of the match but it was Kvitova who pounced again to ensure a tiebreaker would not be needed, wrapping up victory in one hour, 49 minutes with a deep return that Safarova could only thump into the net.
The victory improved Kvitova's head-to-head record to 8-0 over Safarova but the pair will transform from rivals to team mates in Prague on Nov. 14-15 when the Czech Republic take on Russia in the Fed Cup final in search of a ninth title.
The 'Red Group' concludes on Thursday with Simona Halep (1-1) taking on Agnieszka Radwanska (0-2) before Maria Sharapova (2-0) faces Flavia Pennetta (1-1) in the night match.
