By Amy Tennery
NEW YORK, Sept 4 (Reuters) - Emma Navarro stunned Czech seventh seed Karolina Muchova 6-3 7-5 on Friday, notching up her third win over a top-10 opponent this year as she joined the American march into the weekend at the U.S. Open.
The 26th seed did some of her best work from the baseline as she absorbed the blows from Muchova, who had been sidelined after reaching the Wimbledon final in July due to minor surgery.
Navarro next plays either Elina Svitolina or Anna Kalinskaya in the round
of 16.
"I knew it was going to be tough today," said Navarro who joined compatriots Taylor Townsend and Jessica Pegula in the fourth round, with Madison Keys and Coco Gauff yet to play their third-round matches.
After trading breaks, Muchova dropped her serve with a misfiring forehand in the penultimate game of the opening set, where she produced 22 unforced errors and struggled to find her rhythm.
Navarro, who reached the semi-finals two years ago in a career breakthrough, beat down her opponent's defences in a more competitive second set, trading breaks twice before converting on her third break-point chance in the 11th game.
Navarro, a darling of the outer courts who said she has played her last six matches in New York on the Grandstand, thrust her fists in triumph after sealing the win with a lethal forehand.
(Reporting by Amy Tennery in New York; editing by Clare Fallon)
