World No.1 Iga Swiatek became the first Polish woman to reach the US Open quarter-finals on Monday when she defeated Jule Niemeier in an error-strewn last-16 clash. 

French Open champion Swiatek recovered from a set and a break down to see off her 108th-ranked German opponent, 2-6, 6-4, 6-0. Top seeded Swiatek will face US eighth seed Jessica Pegula for a place in the semi-finals.