By John O'Brien
SINGAPORE (Reuters) - Svetlana Kuznetsova claimed her second titanic victory in a row when the Russian outlasted Karolina Pliskova 3-6 6-2 7-6(6) in a thrilling White Group encounter at the WTA Finals to reach the semi-finals on Wednesday.
In the second pool match, Poland's Agnieszka Radwanska got her title defense back on track with an accomplished 7-6(1) 6-3 victory over French Open champion Garbine Muguruza, a result that eliminated the Spaniard.
After battling toe-to-toe for two hours and 17 minutes, Kuznetsova collapsed in a heap on the court after sealing victory on her fourth match point with a backhand winner down the line to finally break the Czech's resistance.
"With all the support of the crowd and my team, I couldn't afford to let myself and everybody down so I had to fight," twice grand slam winner Kuznetsova said.
"I haven't been at my best in recent years but something changed this year... I enjoy my game, I enjoy the crowd and I feel blessed to be playing the best players in the world."
Kuznetsova was the final qualifier for the elite eight-woman event when she successfully defended her Kremlin Cup title on Saturday and the world number nine has shown incredible staying power to first outlast Radwanska on Monday and now Pliskova.
The victory had put Kuznetsova on the verge of sealing a semi-final spot at the year-end championships for the first time in six attempts and her berth was assured when Radwanska beat Muguruza in the late match.
Pliskova started confidently, pushing her opponent around the court with her booming forehand and holding comfortably despite struggling to find her range with the first serve, the Czech edging ahead first with a break in the fourth game.
As in her win over Radwanska, Kuznetsova grew into the match and grabbed her first break in the seventh game but the Czech struck back immediately to regain the initiative.
The big-serving Pliskova consolidated the break with the easiest of holds, rattling through her next service game without dropping a point as she sealed the opening set in 33 minutes.
Kuznetsova was still moving tentatively and Pliskova took full advantage to forge another break of serve in the first game of the second set but the Russian found her rhythm as her opponent wavered to stage an impressive fightback.
The 31-year-old Russian broke back immediately to prevent Pliskova from running away with the contest and then reeled off five of the next six games to send the match into a decider.
With both players emerging from three-setters on Monday the fatigue finally kicked in and neither was capable of holding serve, so after combining for eight breaks in the set, it was only fitting the match would be decided in a tiebreak.
Service woes also littered the match between Radwanska and Muguruza with three breaks apiece sending it into a tiebreak which Poland's world number three sealed with a spectacular backhand winner as she captured the last six points in a row.
Radwanska shrugged off an early break in the second set to overwhelm Muguruza with exceptional shot-making and brilliant service returns, closing out the 96-minute contest on her first match point with her sixth break of the match.
Radwanska and Pliskova meet on Friday with the winner advancing along with Kuznetsova to the semis.
(Editing by Ken Ferris)