NEW YORK, NY, USA - No.16 seed Elise Mertens snapped Sofia Kenin's Grand Slam winning streak, upsetting the American, 6-3, 6-3 to return to the last eight of the US Open.

"I played pretty aggressively from the first ball, and that's pretty necessary against her because she's a great player who can hit a lot of great angles," she said during her on-court interview. "I tried to step into the court, and thankfully my first serve was working, so that was a big advantage."

Kenin had won her last 10 major main draw matches after hoisting her first Grand Slam title at the Australian Open in January, but the Belgian proved too strong on Monday evening, advancing after 74 minutes on Arthur Ashe Stadium. 

Kenin and Mertens clashed twice in 2019, with the American narrowly winning both encounters in three sets at the the Mallorca Open and the Dongfeng Motor Wuhan Open. 

"It's always good to watch matches against players you've lost to, because you know you have to do better. I actually watched the Wuhan match, but most importantly I tried to stay focused, and that's what I did tonight."

The reigning Australian Open champion rolled into the second week of the US Open for the first time without dropping a set, but struggled early on against the No.16 seed, who pushed eventual champion Bianca Andreescu to three sets on Arthur Ashe Stadium in the quarterfinals last year.

An Australian Open semifinalist in 2018, Mertens surged ahead by a double break and held a set point at 5-1.

Kenin began to come alive from there, saving a second set point to get one of the breaks back, but Mertens was unmoved, breaking straight back with a searing backhand winner to take the opening set.

Looking to gain early momentum in the second, the American struck an impressive backhand of her own to score the first break point of the set. 

Mertens saved it and earned three break chances of her own in the sixth game, converting as Kenin erred wide on a crosscourt backhand.

Another backhand miss handed Mertens a trio of match points, but the Belgian only needed one, sealing the win with an ace down the T.

"I had a lot of energy and stress at the end, but I really tried to take things point by point, and I'm really glad to be in the quarters.

"It means a lot because a lot is going on in the world and I'm just glad to be back and playing matches, doing what I love."

In all, Mertens played a pitch-perfect match, striking 19 winners to just seven unforced errors in two sets, putting down seven aces while converting four of nine break point opportunities. Kenin, by contrast, took more risks throughout and ended with 23 winners to 26 unforced errors, and managed just two break point opportunities.

Up next for the former World No.12 is two-time US Open runner-up Victoria Azarenka, who finished 2019 Wimbledon quarterfinalist Karolina Muchova in three sets on Louis Armstrong Stadium.

"Azarenka's a great player. She won Cincinnati so she's really on fire."

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