ISTANBUL, Turkey -- World No.2 Caroline Wozniacki staged a comeback in the second round of the TEB BNP Paribas Istanbul Cup on Thursday, overcoming former World No.5 Sara Errani, 5-7, 6-3, 6-3 to reach the quarterfinals after a grueling encounter.

"In the first set, I made way too many unforced errors, but I kind of cut that down in the second and third set," Wozniacki told the press, after the match.

"On the clay, it’s important to be able to play defense, because there’s longer rallies, but at the same time, if you have a short ball, you have to attack," Wozniacki continued. "I’m trying to find that balance. It’s not easy, especially in the first tournament of the year."

Top-seeded Wozniacki led their head-to-head record 3-1 coming into the match, including a 6-0, 6-1 dismantling in their most recent meeting at the 2014 US Open. But the reigning Australian Open champion had a much more difficult time with 2012 Roland Garros runner-up Errani than she experienced in her opening round.

Errani’s clay-court prowess was in full effect throughout the match before Wozniacki regrouped to ultimately prevail in two hours and 26 minutes. The Danish star had 47 winners to Errani's 23, and broke Errani six times in the match. Errani also broke Wozniacki five times in the closely contested tilt.

Wozniacki will now take on France’s Pauline Parmentier in the quarterfinals. The 32-year-old Frenchwoman, coming off a Fed Cup weekend in which she gave Sloane Stephens and Madison Keys close matches, moved past Kazakhstan’s Yulia Putintseva on Wednesday, 6-2, 2-6, 6-3, to reach her first quarterfinal of the year.

"She likes the clay for sure," said Wozniacki, who has a 3-0 head-to-head lead over Parmentier. "I don’t remember when I played Pauline the last time, but it’s not going to be easy, again. I’m just trying to find more rhythm here on the clay courts, and trying to play my best tennis."

In other second-round matches on Thursday, Donna Vekic of Croatia rolled past Australia's Ajla Tomljanovic, 6-1, 6-2, Greece's Maria Sakkari outplayed Aleksandra Krunic of Serbia, 6-3, 6-1, and Dutchwoman Arantxa Rus overcame Danka Kovinic of Montenegro, 2-6, 6-2, 6-0, in a battle between qualifiers. Also, Slovenia's Polona Hercog advanced when Kateryna Bondarenko of Ukraine retired while trailing 6-2, 1-1.

Errani was in early control of the opening set. At 2-2, Wozniacki misfired long on the final two points of the game, as Errani valiantly chased down all of Wozniacki’s shots, maneuvering the top seed into errors and the first break of the match.

Errani then leapt out to a 5-2 advantage by breaking Wozniacki again on her fifth break point of the game, with crafty drop shots and perfectly placed lobs supplementing more strong defense by the Italian to give her the commanding lead.

Slowly but surely, Wozniacki pulled herself back into the match. The Dane saved a set point on Errani’s serve with extravagant defense of her own, eventually claiming one break back after a long forehand by the Italian. Errani had a second chance to close out the set in her next service game, but a soundly struck Wozniacki backhand forced an error from the World No.93, en route to leveling the set at 5-5.

However, another long game at 5-5 eventually went the way of the Italian, when Wozniacki double faulted to give Errani a sixth break point in the game, which was converted after Errani crushed a forehand service return winner. At 6-5, Errani reached set point for a third straight service game, and she was finally able to take the opening frame on her fourth set point.

Despite the loss of the set, Wozniacki had greatly improved as the match wore on, and that momentum persisted as she raced out to a big lead in the second set. Strong returning by the World No.2 pressured Errani into greater risks on her serve, which led to instances like when the Italian double faulted while down break point, handing a 4-0 lead to Wozniacki.

Wozniacki hit three backhand winners to hold for 5-2, as her favored wing found its range in the second set. Two games later, the No.1 seed lost one set point with a wide forehand, but converted her second opportunity with another backhand winner, tying the match at one set apiece.

Afterwards, Wozniacki identified "getting my backhand working, trying to eliminate those unforced errors I was making" as the key to victory.

The sturdy play by Wozniacki continued in the deciding set, as the Dane countered Errani's spin and angles with incredible depth of shot. Wozniacki claimed a quick break in the opening game of the set, and cracked the decider wide open with a backhand winner in the corner to clinch a 4-1, double-break lead.

Errani's wily tennis helped her get one break back, punching a volley for a winner to get to 4-2. The Italian then held for 4-3, hoping for another chance to pull even. But former World No.1 Wozniacki would not be deterred, easily holding for 5-3 via another backhand winner, and breaking Errani in the final game to emerge victorious after a lengthy battle.