Murray’s stirring five-set comeback against Thanasi Kokkinakis of Australia ended a day that also saw the men’s singles favorite Novak Djokovic win while playing with a hamstring injury.MELBOURNE, Australia — It was a night worthy of a knight, and Sir Andy Murray’s stirring comeback victory from two sets down against Thanasi Kokkinakis at the Australian Open also turned into one of the latest nights in tennis history.That is saying something in a sport that is often, too often, played into the wee hours of the morning, but Murray, a stouthearted Scotsman now playing tennis with an artificial hip, needed 5 hours 45 minutes to find a way to prevail against Kokkinakis, a big-serving Australian nearly 10 years his junior.Murray’s win, 4-6, 6-7 (4), 7-6 (5), 6-3, 7-5, began Thursday and finished Friday at 4:05 a.m. with several thousand die-hard fans still making plenty of noise in Margaret Court Arena as some waved British flags for Murray and Australian and Greek flags for Kokkinakis.The end finally came with the 35-year-old Murray breaking serve at 5-5 and then holding his own to finish off the longest match of his career and earn, truly earn, a spot in the third round.The Australian Open has brought him plenty of heartache — he has lost in the final a record five times — but it is bringing him plenty of fulfillment this year.In the first round on Tuesday, he saved a match point and upset the No. 13 seed, Matteo Berrettini of Italy, prevailing in a fifth-set tiebreaker after 4:49.The duel with Kokkinakis, a 26-year-old wild-card entrant ranked 159th in the world, lasted nearly a full hour longer. But the quality and tenacity of play was often extraordinary down the stretch despite all that time on the court.“I just rely on that experience and that drive and my love of the game and competing and my respect for this event and the competition,” Murray said. “That’s why I kept going.”This was the third-latest recorded finish in the history of professional tennis, surpassed only by Alexander Zverev’s victory over Jenson Brooksby in Acapulco, Mexico, last year that ended at 4:54 a.m., and by Lleyton Hewitt’s victory over Marcos Baghdatis at the 2008 Australian Open that ended at 4:34 a.m.The 2023 Australian OpenThe year’s first Grand Slam tennis tournament runs from Jan. 16 to Jan. 29 in Melbourne.Taylor Townsend: A decade ago, she had to contend with the body-shaming of tennis leaders in the United States. Now, she’s determined to play the best tennis of her career.Caroline Garcia: The top player has spoken openly about her struggles with an eating disorder. At the Australian Open she is chasing her first Grand Slam singles title.Talent From China: Shang Juncheng, once the world’s top-ranked junior, is the youngest member of a promising new wave of players that also includes Wu Yibing and Zhang Zhizhen.Ben Shelton Goes Global: The 20-year-old American is ranked in the top 100 after a late-season surge last year. Now, he is embarking on his first full season on tour.It is a dubious honor to be on that list, but Brooksby, a 22-year-old Californian, at least got to play in the daylight on Thursday. He recorded the most significant victory of his career by upsetting the No. 2 seed Casper Ruud of Norway, 6-3, 7-5, 6-7 (4), 6-2, in Rod Laver Arena in the second round.That came less than 24 hours after Mackenzie McDonald, 27, another unseeded Californian, upset the injured Rafael Nadal, the No. 1 seed and the reigning champion, on the same court.Jenson Brooksby won Thursday against Casper Ruud, 6-3, 7-5, 6-7 (4), 6-2, at the Australian Open.Carl Recine/ReutersIn all, eight American men reached the round of 32 in Melbourne, the most at this Grand Slam tournament since 1996 when Pete Sampras and Andre Agassi were still in their primes.“First and foremost, Casper is a warrior,” Brooksby said. “I knew it would be a great battle out there. I was pretty confident with my level and just wanted to have fun competing.”Nadal, however, will not compete for at least a few weeks. He announced on Thursday that he had undergone a magnetic resonance imaging scan that showed an injury of the iliopsoas muscle in his left inner hip.Nadal, 36, will return to Spain for treatment and, according to his team, “the normal time estimated for complete recuperation is between six and eight weeks.” That would likely mean that Nadal will miss the next block of hardcourt events, including the BNP Paribas Open in Indian Wells, Calif. But if he recovers, Nadal could be ready to compete during the clay-court season. He has dominated on clay for close to two decades and could aim for a 15th singles title at the French Open.But Novak Djokovic, Nadal’s longtime rival who is chasing his record of 22 Grand Slam singles titles, remains in contention in Melbourne despite his own injury challenges. Djokovic, a nine-time Australian Open champion, started the tournament with a nagging left hamstring injury. He aggravated it on Thursday night in his victory, 6-1, 6-7 (5), 6-2, 6-0, over Enzo Couacaud, a French qualifier ranked 191st who sprained an ankle early in the match but managed to continue.Late in the second set, Djokovic, with his left hamstring tightly wrapped, began wincing and landing awkwardly on some shots, looking far from eager to slide into his signature defensive splits. He even limped and pulled up as he ran to his left for a backhand at one stage.With a third-round matchup against Grigor Dimitrov scheduled for Saturday, Djokovic conceded that his situation going forward in the tournament was “not ideal.”“I am worried,” he said of his injury. “I mean, I cannot say that I am not. I have reason to be worried. But at the same time, I have to accept the circumstances and try to adjust myself with my team.”Djokovic said he was minimizing or eliminating practice sessions on days between matches. In 2021, he won his ninth Australian Open after tearing an abdominal muscle in the third round.“Somehow I pushed it through and won the tournament,” Djokovic said. “But it’s different now, obviously. I don’t know how my body’s going to react. I hope for the best. I hope for the positive outcome. I’ll take it day by day, match by match and see how it goes.”Novak Djokovic stretched during his second round-match. “I am worried,” he said later of his hamstring injury.Loren Elliott/Reuters Earlier in the day, Ruud, the affable Norwegian star who reached the French Open and U.S. Open finals last year, could not solve the riddle of Brooksby’s unconventional game.Theirs was a grinding match, full of rallies whose shot count extended into double digits. Though Brooksby won the vast majority of those — quite an achievement against a baseliner as accomplished as Ruud — he could not convert any of the three match points he had on his own serve at 5-3 in the third set.Distraught, Brooksby sat in his chair on the changeover shouting “How, how how?”Ruud won the third set in a tiebreaker, which could have been the cue for Brooksby to fold. Instead, he walked back onto the court after a break in the locker room and broke Ruud twice in a row to take a 3-0 lead. Then, after losing his serve, he broke Ruud again at love to reclaim full command of the match.“I’m just really proud of my mental resolve there, after the third-set battle didn’t go my way, to turn it around,” Brooksby said.It was the standout victory of Brooksby’s career, and it was a bad day all around for No. 2 seeds. Ons Jabeur, the No. 2 seed in the women’s singles tournament, was defeated after midnight, 6-1, 5-7, 6-1, by Marketa Vondrousova, an unseeded Czech lefthander.Tennis is a draining, mood-swinging sport, full of surprises, and the bottom quarter of the men’s singles draw is now a zone of great opportunity for outsiders, including the 66th-ranked Murray and five unseeded Americans: Brooksby, Ben Shelton, J.J. Wolf, Michael Mmoh and Tommy Paul.The surprise is that the American men’s surge in Melbourne does not include their leader: the No. 8 seed Taylor Fritz, who was upset on Thursday in five sets, 6-7 (4), 7-6 (2), 6-4, 6-7 (6), 6-2, by Alexei Popyrin, another Australian wild-card entrant.Popyrin will now face Shelton, the 20-year-old son of the former tennis pro Bryan Shelton. Ben Shelton turned professional last year after winning the N.C.A.A. men’s singles title for the University of Florida, where his father is the coach, and is making his first trip outside the U.S.Brooksby will face Paul, and Wolf will face Mmoh, who made it into the main draw as a lucky loser after a withdrawal. Murray, meanwhile, was wondering if he was ever going to get to sleep.“Thanks so much to everyone for staying,” he said to the crowd after his victory. “It’s ridiculously late.” More