A gloomy season that started with elbow surgery following the Australian Open is turning into a brilliant finish for the 31-year-old Serbian who has now won three of his last four events, including back-to-back majors at Wimbledon and Flushing Meadows.

Over the last eight weeks Djokovic has resembled the Grand Slam machine that held all four major titles at the same time in 2016.

Playing on the same court where Pete Sampras claimed his 14th title, Djokovic has endured more disappointment than joy on Arthur Ashe, mining just three titles from eight finals.

The disappointment on Sunday belonged to a teary del Potro who was back in a Grand Slam final for the first time since the big Argentine won his only Grand Slam title at Flushing Meadows in 2009.