World number one Karolina Pliskova of the Czech Republic advanced to the US Open quarter-finals on Monday by routing 91st-ranked American Jennifer Brady 6-1, 6-0 in just 46 minutes. Pliskova, last year's US Open runner-up, will next face either 37th-ranked compatriot Lucie Safarova or US 20th seed CoCo Vandeweghe to decide a berth in the semi-finals.