Hard-hitting Karolina Pliskova put on a serving masterclass to defeat Mariam Bolkvadze 6-1, 6-4 on Wednesday and advance to the third round of the US Open. The towering third-seeded Czech pounded nine aces and won 90 percent of her first-serve points at Arthur Ashe Stadium, which had its retractable roof closed due to rain. World number 202 Bolkvadze, who was playing only her second main-draw match at a Grand Slam, appeared to struggle with nerves in a one-sided opening set. A lengthy battle then ensued with Bolkvadze serving at 2-2 in the second set. Pliskova fired a blistering backhand winner to convert her fourth break point opportunity and extinguish any hope of a comeback for the Georgian qualifier. Former world number one Pliskova, 27, is still searching for her maiden Grand Slam title and the speedy US Open hard courts, where she reached the final in 2016, could provide her with her best opportunity. Next up for Pliskova is a third-round clash with either Ons Jabeur of Tunisia or Aliaksandra Sasnovich of Belarus.