Zheng Qinwen has described her slow return to form as a painful rebirth that left her questioning herself and led to “uncomfortable conversations” with her parents and coaches. After months of struggling on the tour, the Chinese star has returned to form at the US Open, and produced a second thrilling win in a matter of days on Monday in New York, battling back from 5-0 down to beat Iga Swiatek in straight sets to reach the quarter-finals. The former world No 4 has been in such poor form for the...