Britain's Emma Raducanu and Cameron Norrie both secured impressive victories at the Washington Open on Tuesday.
Raducanu upset Ukraine's world number 27 and seventh seed Marta Kostyuk 7-6 (7-4) 6-4 in the first round.
She faces Naomi Osaka next after the four-time Grand Slam winner overcame Yulia Putintseva 6-2 7-5.
In the men's singles, Norrie had to dig deep to beat second seed and world number seven Lorenzo Musetti 3-6 6-2 6-3 - his first success over a top-10 player in two and a half years - in the second round.
The 29-year-old will play American 14th seed Brandon Nakashima in the last 16.