Top seed Karolina Pliskova has been knocked out of the US Open second round in straight sets by Caroline Garcia.
The Czech is third in the WTA rankings but entered the tournament as top seed following Ash Barty and Simona Halep's decision not to take part.
But the 27-year-old, still waiting for her first Grand Slam, never recovered after going down a double break inside 20 minutes against the unseeded French player.
Garcia, ranked 46th in the world and has never surpassed the third round at Flushing Meadows, produced one of the performances of her career to beat Pliskova 6-1, 7-6 in an hour and 33 minutes on Arthur Ashe.
It means that of the top-10 players in the women's singles rankings, Naomi Osaka is the only non-US player who remains in the competition.
In Pictures | US Open 2020
Angelique Kerber, the 2016 champion, had no such problems in brushing aside German compatriot Anna-Lena Friedsam in straight sets.
Eighth seed Petra Martic also made it through unscathed after beating Kateryna Bondarenko on Court 17.
Osaka, winner at the US Open in 2018, is in action in the evening session against Camila Giorgi.
