Emma Navarro produced the biggest upset of this year's US Open on Saturday, knocking out No. 7 seed Karolina Muchova 6-3, 7-5 to reach the fourth round and hand the Czech her earliest exit at Flushing Meadows since 2022.

Navarro, a 2024 semifinalist at the tournament, closed out both sets by winning the final three games in succession, saving her sharpest tennis for the moments Muchova needed hers most. It was the American's first career meeting with Muchova and, according to Yardbarker, her third win over a top-10 opponent since returning from an injury setback earlier this season.

Muchova's Earliest Loss Since 2022

The result is a jarring one for Muchova, who reached back-to-back US Open semifinals in 2023 and 2024 and was a quarterfinalist last year. Saturday's loss was her earliest at the tournament since a first-round exit to Ajla Tomljanovic in 2022, a stunning reversal for a player widely regarded as one of the tour's most dangerous shot-makers on hard courts.

"I'M OVER THE MOON," NAVARRO SAID AFTERWARD, DESCRIBING IT AS ONE OF HER BEST WINS OF THE SEASON.

Speaking to reporters afterward, Navarro said she stayed focused through the tight closing stretches of both sets rather than letting the occasion get to her, calling the win one of her best of 2026, per Tennis Tonic. The victory sends her into the fourth round in strong form, and she'll now be viewed as a legitimate threat to go deep into the second week.

Saturday's action produced ripple effects across the women's draw. Taylor Townsend also advanced with a win over 15th-seeded Diana Shnaider, while Jessica Pegula and Linda Noskova both moved through to keep the round of 16 stacked with contenders. On the men's side, defending champion Carlos Alcaraz cruised past Wu Yibing to set up a fourth-round clash with American Tommy Paul, who needed five sets to get past 15th-seeded Alexander Bublik.

The tournament now shifts into its second week, with Sunday's round of 16 slate featuring Alcaraz-Paul and top-seed Aryna Sabalenka's title defense continuing against American Taylor Townsend. Navarro will learn her next opponent once the round of 16 matches are complete, with a potential path opening toward the second week's marquee matchups if the upsets keep coming.