Qualifier Karolina Muchova knocked out two-time Grand Slam champion Garbine Muguruza in a second-round shocker at the U.S. Open.
Muchova, a 22-year-old Czech who came through qualifying in New York, downed Muguruza, 3-6, 6-4, 6-4, in the second round.
Playing in the main draw of a Grand Slam for the first time, Muchova completed her victory just after 1 a.m. local time Thursday.
Muchova, the world No. 202, held her nerve in the third set, hitting 14 winners and just 11 unforced errors.
A stunning upset in Louis Armstrong Stadium as qualifier Karolína Muchová defeats Muguruza 3-6, 6-4, 6-4!
In just her 3rd tour level match, she will now face Ash Barty in R3…#USOpen pic.twitter.com/0dfiBCWlRb
— US Open Tennis (@usopen) August 30, 2018
The loss marked two-time Grand Slam champion Muguruza’s third second-round exit at majors this year.