New York: Novak Djokovic suffered a shock first-round exit from the US Open on Sunday night, losing to Argentina's Mariano Navone in a five-set marathon.The Serbian fourth seed was beaten 7-6 (5), 5-7, 4-6, 6-2, 6-1 in a match lasting four hours and 36 minutes.The defeat marked the first time Djokovic has lost in the opening round of the US Open and his earliest exit from a Grand Slam tournament since the 2006 Australian Open.The loss came exactly 21 years after Djokovic made his US Open debut and has prompted questions about whether it could prove to be his final appearance at the tournament or at a Grand Slam event.Djokovic, 39, struggled throughout the match, committing 70 unforced errors and appearing to be affected by physical issues.The 24-time Grand Slam champion received medical attention during the contest, taking medication provided by a doctor and undergoing treatment on his lower back between the fourth and fifth sets.Despite taking early leads in the opening set and winning the second and third sets, Djokovic was unable to maintain momentum against the 25-year-old Navone.Navone, who won his first ATP singles title earlier this year, remained composed throughout the contest and secured his first career victory in a five-set match.Djokovic appeared to struggle physically during the final stages of the match and was unable to mount a comeback as Navone dominated the decisive fifth set.The result ended one of the most surprising matches of this year's US Open and marked a rare early departure for one of the most successful players in tennis history.
