NEW YORK — Novak Djokovic is out of the U.S. Open, after losing in New York in a way that he never has before.In a stunning loss that snapped a streak of 77 first-round wins at Grand Slams, Djokovic lost in five sets to Argentina’s Mariano Navone, a top-50 stalwart who has beaten some formidable players but never a true great.Sunday night in Arthur Ashe Stadium, he took down a lethargic and then limping, puking and then cramping, and roaring and then resigned Djokovic 7-6(5) 5-7, 4-6, 6-2, 6-1 in four hours and 36 minutes.Djokovic last lost a first round-match at a Grand Slam at the 2006 Australian Open, when he was the world No. 76. Since then, he had navigated the terrain of major openers as well as anyone, until a harrowing night that left him contemplating his own sporting mortality more closely than he has yet.And yet, through a 73-minute first set and for more than four hours of a long opening night, almost nothing about this match made sense, other than Djokovic being 39.That is well beyond when nearly every all-time great before him has ceased being competitive.Navone sunk a dagger into Djokovic in the second game of the final set, pushing him around the court then drawing him to the net. As Djokovic approached, Navone sent a backhand down the line that Djokovic couldn’t half-volley back over the net. Djokovic staggered on his next steps, then limped and winced through the next games, seemingly becoming too old to compete in real time as the energy of the packed stadium grew funereal.Djokovic’s wife, Jelena, and his children, Stefan and Tara, sat courtside growing more glum by the game.Djokovic had gotten off to a fast start, smacking three aces in his first two service games and sprinting to a 3-0 lead. Quickly though, Navone started to get his teeth into rallies, forcing Djokovic to hit more balls than he wanted to on a dankly humid but hardly hot night.The weather became largely irrelevant seven games into the game, when rain began to fall, the roof closed and the air conditioning clicked on. By then, though, Djokovic had given back that early break of serve and appeared to be struggling physically.In the seventh game of the third set he vomited in a bin on the side of the court in the middle of the gameWhen points stretched beyond a half-dozen shots, Djokovic often leaned over onto his knees before the next one. Throughout the night, Djokovic had a significant edge over Navone on points that were four shots or less. Anything longer than that, the edge went to Navone. When Djokovic’s serve was not enough to get a free or cheap point, and when his return was too much for Navone to do the same, what ensued were energy-sapping rallies that slowly drained Djokovic’s life force.