New York:Juan Martin del Potro became the lowest ranked player in 25 years to reach the US Open quarter-finals Monday, setting up a showdown with fellow Grand Slam title winner, Stan Wawrinka. The 142nd-ranked del Potro was leading eighth-seeded Dominic Thiem 6-3, 3-2 when the Austrian retired with a right knee injury. Del Potro, the […]