Japan’s Risa Ozaki was in impeccable form as she hammered second seed Sloane Stephens 6-2, 6-1 in the first round of Citi Open on Tuesday.
Ozaki, who needed just under an hour to down Stephens, won 68 per cent of points on her first serve and saved two of the three break points she faced.
The 22-year-old will face Naomi Broady in the second round after the Briton defeated Irina Falconi 6-3, 6-4.
Stephens was not the only seeded player to fall in the first round as fifth seed Eugenie Bouchard was beaten 5-7, 4-6 by Camila Giorgi, while eighth seed Monica Niculescu lost to Christina McHale 3-6, 4-6.
Third seed Monica Puig had no such problems as she downed Oceane Dodin 6-2, 4-6, 6-3.
Sabine Lisicki and Tamira Paszek also progressed to the second round after triumphing over Kristina Kucova and Lauren Albanese respectively.