New York - Karolina Pliskova, the 2016 US Open runner-up, became the first woman to qualify for the third round on a rain-hit Wednesday after making quick work of Georgian qualifier Mariam Bolkvadze.
Third seed Pliskova smacked nine aces in a 6-1, 6-4 victory in 66 minutes to maintain her push to regain the world number one ranking.
The 27-year-old needs to reach at least the quarter-finals in New York to stand a chance of usurping reigning US Open champion Naomi Osaka at the top.
US Open results on Wednesday (x denotes seeding):
Roger Federer (SUI x3) bt Damir Dzumhur (BIH) 3-6, 6-2, 6-3, 6-4
Grigor Dimitrov (BUL) bt Borna Coric (CRO x12) walkover
Kei Nishikori (JPN x7) bt Bradley Klahn (USA) 6-2, 4-6, 6-3, 7-5
Elina Svitolina (UKR x5) bt Venus Williams (USA) 6-4, 6-4
Karolina Pliskova (CZE x3) bt Mariam Bolkvadze (GEO) 6-1, 6-4