Sixth seed Madison Keys was sent tumbling out of the US Open on Monday, losing in straight sets to lowly ranked Mexican player Renata Zarazua.
Reigning Australian Open champion Keys bowed out after an attritional battle with Zarazua, who prevailed 6-7 (10/12), 7-6 (7/3), 7-5.
Zarazua, ranked 82 in the world, took advantage of Keys' problems with her service game to claim an impressive win.
Todas las emociones 💚
— US Open Tennis (@usopen) August 25, 2025
Renata Zarazua of Mexico notches the biggest win of her career, rallying from 7-6 3-0 down to stun Keys! pic.twitter.com/NDtoZl6M4F
Keys gave up 14 double faults and was broken six times as Zarazua battled into a second-round meeting with France's Diane Parry.
World No.82 Renata Zarazua becomes the first Mexican woman ever to beat a top 10 opponent at the US Open! 🇲🇽 pic.twitter.com/SiqI4xy4iw
— US Open Tennis (@usopen) August 25, 2025
Keys' defeat comes after a solid season in Grand Slams following her maiden victory at the Australian Open in January. She reached the quarterfinals at the French Open before progressing to the third round at Wimbledon.
Canadian teenager Victoria Mboko was brought down to earth with a straight sets first round defeat to Barbora Krejcikova at the US Open on Monday.
Mboko, the 22nd seed who turns 19 on Tuesday, bowed out of the tournament after losing 6-3, 6-2.
Barbora Krejcikova takes out Montreal champion Mboko in straights! pic.twitter.com/d43ST8JOUc
— US Open Tennis (@usopen) August 25, 2025
The early exit comes just three weeks after Mboko celebrated her first WTA title with victory at the Canadian Open in Montreal.
Two-time Grand Slam singles champion Krejcikova will face Japan's Moyuka Uchijima in the second round.
Elsewhere on Monday, two-time Wimbledon champion Petra Kvitova brought the curtain down on her professional career with a 6-1, 6-0 defeat to France's Diane Parry.
The Pojd Heard 'Round the World.
— US Open Tennis (@usopen) August 25, 2025
Congratulations on an incredible tennis career, @Petra_Kvitova. The US Open wishes you all the best in retirement! 💙🇨🇿 pic.twitter.com/SErbYfAeTS
The 35-year-old Czech had already announced she planned to hang up her racket after the US Open.