NEW HAVEN, CT, USA -- Aryna Sabalenka of Belarus picked up another big victory during the North American hardcourt summer, outlasting No.9 seed and defending champion Daria Gavrilova of Australia, 6-3, 6-7(6), 7-5, to reach the quarterfinals of the Connecticut Open on Wednesday.

"I’m happy that I ended with a win," Sabalenka told the press, after her lengthy rollercoaster encounter. "I don’t know what more to say about this match," she laughed.

After a straightforward opening set went Sabalenka's way, Gavrilova came away with the lengthy, topsy-turvy second set, and Sabalenka had to right the ship to claim a grueling decider and pick up the victory after two hours and 46 minutes of play.

"All match was up and down, and I always tried to turn it around," said Sabalenka. "Sometimes it worked, sometimes it worked on her side."

"[Gavrilova's] a great player, she’s moving good, she put a lot of balls back," Sabalenka continued. "In the third set, I started to be more calm, and then it’s 4-0, and I don’t know what happened -- from that moment, it’s going down again, then up, down, up. I’ve never had this match before, it’s unbelievable."

Sabalenka survived 15 double faults and 62 unforced errors by blasting 45 winners past Gavrilova, 18 more than the Australian had in the match. The two players combined for 16 service breaks out of 36 break points during the unpredictable encounter.

World No.25 Sabalenka is on a roll since her semifinal run at the Western & Southern Open last week. The 20-year-old will face lucky loser Belinda Bencic in the quarterfinals, after the former World No.7 from Switzerland dispatched qualifier Camila Giorgi of Italy in the second round on Tuesday.

"[Bencic] has a good character on the court, so she will fight, it doesn’t matter what," said Sabalenka. "It will be one more challenge for me, but I will do my best tomorrow."

Sabalenka took the immediate initiative, fending off two break points on her serve at 1-1 before breaking World No.24 Gavrilova for a 3-1 lead with a screaming forehand crosscourt winner. But the defending champion quickly found herself back on serve as Sabalenka fired three double faults in her next service game.

Nevertheless, Sabalenka kept trying to dictate play with her forehand, and she once again claimed a break advantage, as 24-year-old Gavrilova dropped serve at 4-3 from 30-0 up, due to a succession of wide forehands.

Serving for the one-set lead, Sabalenka overcame two more double faults to close out the opening frame after Gavrilova shot a service return wide on the Belarusian’s second set point. Sabalenka had 10 winners to Gavrilova’s three in the first set; the Australian also was undone by 11 unforced errors.

After starting the second set by falling down an early break, Gavrilova picked off five of the next six games to take command, using strong returning and her patented footspeed to control points and draw Sabalenka into errors, en route to a 5-2 lead.

With Sabalenka serving in that game, a return winner by Gavrilova gave the Australian double set point. But at that juncture, the Belarusian started to hit out even more on her shots, and blasted her way to a hold. Sabalenka then kept crushing groundstrokes, winning four games on the trot and giving herself a chance to serve out the match at 6-5.

But miscues by Sabalenka squandered that chance, and Gavrilova broke without ever having to face a match point. In the tiebreak, Gavrilova jumped to a 6-3 lead; Sabalenka saved the third and fourth set points with huge serving, and Gavrilova double faulted away the fifth, knotting the breaker at 6-6. But two points later, a Gavrilova pass forced an error from Sabalenka, and the match was all square.

Sabalenka, though, dominated in the early part of the deciding set. She reached break point in Gavrilova’s first service game of the third set with a forehand return winner down the line, and garnered the break after Gavrilova double faulted. Two games later, another return winner off the forehand side gave Sabalenka a huge 4-0 lead.

The Belarusian had triple break point to lead 5-1 before more solid Gavrilova defense allowed her to hold for the first time in the set and reach 4-2. Suddenly, the speedy Aussie was coming up with the goods at the ends of rallies, and using her own forehand to force the issue, collecting four games in a row to tie the set at 4-4.

Serving at 5-6, Gavrilova reached double game point, and a decisive tiebreak seemed in the offing. But Sabalenka turned on her forehand when necessary, wallopping shots from that wing to reach the first match point for either player. There, a rally ended with the defending champion sending a backhand long, and a relieved Sabalenka moved into another WTA quarterfinal.