DUBAI, UAE - No.2 seed Petra Kvitova overcame stern resistance from qualifier Jennifer Brady before making her way into the Dubai Duty Free Tennis Championships quarterfinals for the first time in six years 7-5, 1-6, 6-3 after two hours and 12 minutes.

"Definitely it's a relief right now," Kvitova said afterwards. "But I think in couple of minutes or hours, it will be really exhausting... The wind was just terrible today, to be honest. It was really difficult to find a way with it. I couldn't really serve well today at all. It's been big struggle for me."

The first meeting between the pair found both taking some time to get to grips with each other's heavy-hitting games - as well as finding their own range. A swashbuckling net-rush off return was a statement of intent from Kvitova in the first game, but Brady came up with big serves to dig herself out of a 0-40 hole.

Indeed, the Brady serve would be one of the American's biggest weapons - but not an especially reliable one initially. The World No.117 would win 92% of the points behind her first delivery in the opening set - but landed it just 38% of the time, and committed one double fault in four of her first five service games.

One of those paved the way for Kvitova to capture the first break for 3-2, sealing it via a tactic that would pay dividends on several occasions: hammering the ball directly at Brady, rushing the 23-year-old's forehand and its long take-back. Brady's backhand, however, was much sturdier - and would rise to the occasion to help the former World No.60 break straight back immediately.

Serving to stay in the set at 4-5, 15-15, Kvitova found the key to the set. With Brady dominating the point, the Australian Open finalist desperately scrambled to stay in the point before hoisting a marvelous lob over her opponent's head - and, instead of being two points from losing the set, instead triggered a run of eight consecutive points and 14 of the next 16 for the Czech. Seizing the set in style, Kvitova finessed a dropshot to break Brady and fired a forehand winner down the line on her second set point.

The 2013 champion's purple patch was all too brief, though. Facing four break points in the first game of the second set, Brady gathered herself to hit out bravely and fend all of them off with big groundstrokes - and now it was Kvitova's turn to be plagued by double faults.

A fourth and fifth put the Sydney champion down 0-2, and two games later a sixth and seventh extended the deficit to 0-4. Though Kvitova managed to stave off two points for the bagel set, the second act was something of a nightmare nonetheless as she committed 16 unforced errors in just seven games.

"That was probably the worst game which I played," Kvitova recalled of her first service game in the set. "I didn't make it. I really felt big, big chance there. But ... mentally I just dropped and I can't really handle it, my serve afterwards. I lost that game. From that time, it was really quick."

Brady, for her part, is back in form after dropping out of the Top 100 last year, and is coming off the second and third Top 20 wins of her career - over Caroline Garcia in both Hua Hin last month and in yesterday's second round here, a run that will see her rise back into the Top 100. She would raise her first serve percentage to 50% and keep her own ground game watertight, with just four unforced errors and seven winners - the last of which came with a forceful backhand down the line to take her fourth set point.

After overcoming Katerina Siniakova in a gruelling second-round encounter yesterday, Kvitova had tweeted that she was "glad P3tra came back" - and she would be forced to draw on her renowned three-set record once again today. The two-time Wimbledon champion flicked the switch just in time: an eighth double fault opened the door for Brady to break in the very first game, but Kvitova was able to save two break points with unreturnable serves - and then capture a break herself as Brady offered up a sixth double fault of her own and a slew of errant groundstrokes.

Kvitova's touch was now firmly back, as the 28-year-old demonstrated by pulling up some delightful finesse shots as she extended her lead: a perfect dropshot, a touch volley winner hit from near her ankles, a pinpoint lob.

To her credit, Brady didn't allow Kvitova to run away with the decider, forcing the World No.4 to save a break-back point in the seventh game; Kvitova, though, saved that with her fifth ace of the day. Even a tenth double fault on her first match point was just a minor blip now as Kvitova sealed victory with a wonderful, athletic all-court point finished smartly at the net. Up next will be another unseeded player in Viktoria Kuzmova, who remarkably saved match point for the second match in a row to make her first Premier quarterfinal.

Having fended off one match point against No.7 seed Kiki Bertens yesterday, the Slovak saved three more while trailing fellow 20-year-old Sofia Kenin 1-6, 3-5 today before running away a 1-6, 7-5, 6-2 winner.