WHAT HAPPENED: No. 26 seed Aryna Sabalenka continued her magical summer on Saturday night, defeating No. 5 seed Petra Kvitova, 7-5, 6-1, in Louis Armstrong Stadium. The win puts Sabalenka into the fourth round of a Grand Slam for the first time.

“I’m in shock a little bit, but I’m so happy,” said Sabalenka in her on-court interview. “I really like to play in the big stadiums and feel the support of the people. I didn’t expect anything today. I was just focused on every point.”

On paper, the odds were against Sabalenka. The 20-year-old Belarusian is making her first main draw appearance at the US Open, had never won a main draw match on a show court at a Grand Slam and lost to Kvitova in their only previous meeting this year, in Miami.

Despite that, Sabalenka’s poise made it seem like it was just an ordinary day at the office. She stood toe-to-toe with Kvitova in the quality baseline rallies and long games that highlighted the opening set, with six of the first nine games going to deuce. Sabalenka broke Kvitova twice with fearless play and eventually took a 5-3 lead.

 “I really like to play in the big stadiums and feel the support of the people. I didn’t expect anything today. I was just focused on every point.”

Her inexperience only showed when she attempted to serve out the set at 5-4, with a pair of nervy errors and a big backhand return from Kvitova leveling the match at 5-5. But rather than get rattled, Sabalenka regrouped and immediately broke Kvitova in the next game. The No. 26 seed made sure to convert on her second chance, hitting four straight winners to take the early advantage after one hour of play.

play video AI Match Highlight: Kvitova vs. Sabalenka - Round 3

But while Sabalenka maintained her level in the second set, Kvitova’s faltered considerably. Sabalenka adjusted accordingly, dialing down the aggression and allowing her opponent to implode in the baseline rallies. The Belarusian won the last six games of the match as Kvitova hit 11 unforced errors throughout them. A double fault on match point wrapped up the contest after one hour and 25 minutes, and Sabalenka raised her arms in disbelief.

WHAT IT MEANS: Sabalenka has now defeated five Top 10 players (Caroline Wozniacki, Caroline Garcia, Karolina Pliskova, Julia Goerges and Kvitova) in the last four weeks, posting a 14-2 record in that time. She’s also riding an eight-match win streak, the longest of her career, after winning her first WTA title last week in New Haven.

Ranked No. 111 at this time last year, Sabalenka will now be firmly entrenched inside the Top 20 of the WTA rankings after her run in New York. But when asked to explain her rapid rise up the rankings, she was as direct as her aggressive style of play might suggest.

“I think I put more balls in [than last year],” she said. “That’s enough.”

Next up for Sabalenka will be another hard-hitting baseline battle against Naomi Osaka, who defeated Aliaksandra Sasnovich earlier in the day without dropping a game.

MATCH POINT: Kvitova’s loss tonight makes 2018 the first year in her career that she has failed to reach the second week at a Grand Slam.