NEW YORK, NY, USA - No.9 seed Aryna Sabalenka pulled off a dramatic comeback under the Louis Armstrong Stadium lights to defeat countrywoman and former World No.1 Victoria Azarenka, 3-6, 6-3, 6-4 at the US Open.

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"I was getting crazier with every point, wondering why I couldn't control anything on this court," Sabalenka admitted after the match. "From there, I started to control my emotions, play each point like it's the last one of the match and try to make it interesting for her."

Sabalenka made her major breakthrough in Flushing Meadows last year - reaching the fourth round and falling in three tough sets to eventual champion Naomi Osaka - and showed off similar fight when it mattered most against the two-time finalist to win after two hours and 13 minutes.

"I feel like it's a big win for me because I'm happy I could find something in the important moments, which helped me stay in this big fight. It feels like an important win."

The Belarusian made her Top 10 debut earlier this year after a stellar 2018 season, during which she won her first Premier 5 title at the Dongfeng Motor Wuhan Open, but dealt with inconsistency since, reaching just two WTA semifinals between February and May and losing before the second week of all three major tournaments this year.

Still, Sabalenka showed signs of life during the North American hardcourt swing - where she first began her surge 12 months ago - with a runner-up finish at the Mubadala Silicon Valley Classic.

Against Azarenka, she nonetheless fell behind an early break in what was her first meeting with her compatriot.

"I know she's a great player, especially playing someone else from Belarus, it's extra tough because both of you want to win and it's really important for both us. I couldn't control my emotions in the first set, but I'm happy I could get smoother on the court."

Azarenka, who made the third round of Wimbledon but didn't win back-to-back matches on the summer hardcourts, continued to press the Sabalenka serve, securing another break to claim the opening set.

She moved ahead 2-0 early in the second set before the No.9 seed caught fire, reversing the deficit to lead by a break of her own, breaking once more to level the match.

The deciding set was a tense affair; besides an early exchange of breaks, the two Belarusians held on until the decisive tenth game, when Azarenka sprayed a forehand wide to put Sabalenka over the finish line and into the second round.

"It was a really high level today, and I'm just happy that in the last two games, I didn't put any pressure on myself. I forgot everything and stayed focused on each shot. I didn't think about anything else, and maybe that's why it felt like every point was something unbelievable."

In all, she struck a solid 42 winners to 43 unforced errors while converting four of nine break point opportunities. Though Azarenka struck fewer errors with a total of 27, she also ended the match with only 17 winners.

Awaiting the 2019 Shenzhen Open champion is good friend Yulia Putintseva, who eased past American Madison Brengle in a late match that took place on Court 13.

"We've had some fun in the past, like when we went to a restaurant, I paid for the meal, and she told me next time she'd pay. A few days ago, she let me know that we'd play each other if we won our first rounds, so she suggested we celebrate before that match if it happens. We joked about putting something in each other's food!

"As a player, she's a great player, playing well right now, and beating a lot of top players. She's quick and her game is very fast, and aggressive. It's a tough opponent, but I'll do everything to prepare myself and be ready to compete on this level. If I win, she should have to pay, but I will probably pay anyway!"