ISTANBUL, Turkey -- No.6 seed Petra Martic of Croatia keeps her quest for a first WTA singles title alive after a grueling 7-6(4), 4-6, 7-6(2) win over former Top 10 player Kristina Mladenovic of France in the quarterfinals of the TEB BNP Paribas Istanbul Cup on Friday.

"That's probably one of the longest matches of my life," Martic exclaimed to the media, after her win.

Having split her first two meetings with Mladenovic, it was World No.40 Martic who claimed victory in the rubber match, needing three hours and 17 minutes to triumph in the longest match of the year up to this point. The Croat was the only seeded player to reach the quarterfinals this week.

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The players were separated by whisker-thin margins: both had 46 winners, and Mladenovic had just one more unforced error than Martic. Each woman was fearless when facing break points, with Martic saving nine of 17 and Mladenovic fending off 12 of 19.

"The level was good but we couldn't always convert our chances - and we had many!" said Martic. "But I'm just happy I managed to win. I feel pretty tired but adrenaline is still going and keeping me on my feet. I just hope I can recover for tomorrow."

In the final four, Martic will face the winner of the all-Russian encounter between Margarita Gasparyan and qualifier Veronika Kudermetova.

Both players were using all portions of the court throughout the first set, as dropshots came out often and Martic in particular regularly charged the net to finish off points there. Three consecutive service breaks early in the opener ended with Martic up 4-2, after Mladenovic dropped serve with a double fault on break point.

Martic served for the set at 5-3, but the Croat fired four consecutive errors to drop serve at love. Martic then had five set points on the Mladenovic serve at 6-5, but the Frenchwoman came up with big serves or fiery forehands to keep herself alive, eventually eking out a gutsy hold and sending the set into a tiebreak.

At 3-3 in the tiebreak, Martic’s net play paid off, as two consecutive points were won with brave stab volleys to put the Croat up 5-3. At 5-4, Martic knifed a slice backhand down the line to force an error, giving her a sixth set point. There, Martic finally closed out the set after 68 minutes with a series of ferocious forehands.

The second set was extremely topsy-turvy. Martic was unable to convert any of three break points in the first game, and Mladenovic then took an initial lead when she blasted a forehand crosscourt to convert her fifth break point of the following game and lead 2-0.

Martic, however, rebounded from a 3-0 deficit by breaking Mladenovic twice in succession, with dropshot winners on break point each time, during a four-game run that put the Croat up a break at 4-3. Mladenovic, though, leveled at 4-4, using a thunderous forehand return to punish a weak second serve on break point.

Mladenovic polished off her second three-game streak of the set by breaking Martic once more at 5-4, after Martic squandered a strong serve by blasting a forehand mistake wide on Mladenovic’s second set point. Mladenovic minimized her unforced errors to grasp the second set; the Frenchwoman had only nine miscues, and 15 winners to help her tie the match.

Martic took an early 2-0 lead in the decider, and staved off two break points to hold for 3-1, with a backhand winner down the line and a brilliant dropshot, respectively. But the Croat was unable to hold her lead, and fired a plethora of errors to allow Mladenovic to even the scoreline at 3-3, as a marathon match became more apparent.

The players exchanged breaks twice over the next four games, as Martic would grasp break leads for 4-3 and 5-4, only to have Mladenovic wrest those advantages back with some well-timed groundstroke winners. Mladenovic then took a lead with a hold for 6-5, but Martic used the dropshot again to ease her way to a hold for 6-6.

A tiebreak was pressed into service to settle the barnburner, and Mladenovic did herself no favors with three consecutive unforced errors wide to fall behind 5-1. Martic stayed sturdy and drew an error at the end of a long rally to reach 6-2 and quadruple match point. The Croat only needed one after another wide error by the Frenchwoman, clinching victory in the longest match of the season to date.

More to follow...