The first night session of the US Open this year was approaching the three hour mark when Novak Djokovic walked briskly to the corner of the vast Arthur Ashe Stadium court, bent down and vomited the contents of his stomach straight into the towel bin.This was neither the first nor the last time that Djokovic threw up during an excruciating four hours and 36 minutes of suffering, and his miserable night ended around midnight with the 24-time grand slam champion in tears as he was defeated 7-6 (5), 5-7, 4-6, 6-2, 6-1 by Mariano Navone in the first round.Djokovic’s appearance here marked a record-extending 84th outing at a grand slam tournament but it produced one of his most abject defeats. This is just the third time in the 39-year-old’s career that he has lost in the first round of a major and the first time he has done so since the 2006 Australian Open, over 20 years ago, when he was 18 years old. Perhaps the most startling part of this loss was how early Djokovic’s suffering had started. Before he had even consolidated his opening break at 2-0 in the first set, barely 15 minutes into the match, Djokovic already appeared to be struggling with the humidity even though the match was played in less extreme conditions at night.Over the course of the subsequent five sets, Djokovic appeared to be in a daze on the court, alternating between panting desperately from behind the baseline, vomiting, struggling to find his balance and fighting off cramps. By the end of the match, he had nothing left to give.This was not merely an unlucky illness that struck Djokovic at an inopportune time. Just a couple of weeks ago at the Cincinnati Open, Djokovic struggled badly in similar evening humidity against another Argentinian opponent who did not appear to have any issues in the conditions, with Thiago Agustín Tirante defeating Djokovic in three sets.Djokovic tries to cool down during a break in play. Photograph: Robert Deutsch/IMAGN IMAGES/ReutersAfterwards, Djokovic said that a particular health condition, accentuated by the heat and humidity, was behind his physical struggles. He reiterated those sentiments after this latest painful loss. “I think it was obvious that an awful feeling on the court for me,” Djokovic said. “It is something that I’ve been carrying, unfortunately, pretty much every match this year. You know, vomiting, throwing up, serious issue there, and then my whole body starts to collapse, basically cramping and pain, and the back just gave up in the end, and shoulder, and I couldn’t close it out, break up in the fourth, but just struggled all the way since the fourth game of the match. And again, don’t want to take too much out of his win. Congrats to him; he’s a nice guy, fighter, but you know, I didn’t enjoy myself.”Although Navone is a tough competitor who has impressively re-established himself inside the top 50 after nearly exiting the top 100 last year, nearly all of his best results had come on clay. This was, on paper, a kind first round draw for Djokovic and seemingly a chance for him to start his tournament quickly and conserve energy.Instead, it took just 20 minutes for the drama to begin. Midway through the first set, Djokovic began to cough and splutter from behind the baseline, repeatedly bending over. At 4-3, rain led the tournament organisers to close the Arthur Ashe Stadium roof.Navone celebrates the biggest win of his career. Photograph: Frank Franklin II/APFrom that point until the end of the match, this was an uncomfortable spectacle. While Navone looked completely unaffected by the conditions, Djokovic lathered himself with ice cloths to cool down and at 5-4 in the opening set, the doctor provided him with pills. Despite his struggles, Djokovic served great for a large part of the match, which allowed him to hang on for so long.Navone, meanwhile, has long dreamed of a moment like this. The 25-year-old considers Djokovic his idol, and not long after the draw was revealed, fans uncovered proof of his fandom in the form of a 13-year-old Navone’s tweets from 2014. A large number of Navone’s old tweets on his X account were devoted to supporting Djokovic. His parents had not planned to attend the US Open this year, but the draw forced them to abort their Caribbean holiday and fly to New York.On the most significant occasion of Navone’s career, he played a good match, chasing down every ball, maintaining immaculate length off both wings and forcing Djokovic into bruising extended exchanges that the Serb was in no condition to handle. However, Djokovic spent most of the night barely hanging on. He vomited numerous times throughout the match and by the fourth set he started to fight off cramps. Djokovic’s brilliant serving and eternal fight kept him alive for much of his time on court and he established a two sets to one lead with a break in set four. By the fourth set, however, his legs were heavy and his first serve deteriorated. Not long after that, Djokovic was walking off the court and back to the locker room in tears having suffered another brutal reminder of the difficulties of competing at the highest level at such an advanced age.