Update: On Monday, a little more than 24 hours ahead of his scheduled first-round match, Nick Kyrgios withdrew from the Australian Open with a knee injury.MELBOURNE, Australia — Nick Kyrgios is finally home.He is in Australia, with his people and in the place he longs for during all those homesick months living out of a suitcase on the professional tennis road.For months, he soaked up the sun and trained in Sydney. But he also squeezed in a bit of time, though never enough for his liking, on the black couch in his childhood home in Canberra, Australia’s quiet, rural capital, telling his mother how safe he feels while she drinks tea a few feet away in the kitchen. He could sleep in his old room, where his cherished collection of colorful basketball shoes lines the shelves. That is next to the room with hundreds of his trophies and plaques and dozens of his smashed rackets. His pet macaw is in an aviary out back. Mornings bring brisk, 12-kilometer walks with his father, his golden retriever King and his miniature Dachshund Quincy, up nearby Mount Majura.He hit balls, and lifted weights, goofed around with and gave endless swag to the children at the tennis center in Lyneham where he got his start. Like many in Australia — and lots of other places these days — they worship their local folk hero, no matter how boorish and aggressive he can be in the heat of competition, or when a live microphone appears at his chin. Or maybe that’s why they do.Now though, everything is suddenly different.Last year, Kyrgios evolved from a temperamental talent with so much unrealized potential into the kind of transcendent showman that this supposedly genteel sport offers up every so often — the gifted bad boy who drives the tennis establishment mad but enthralls crowds in the late stages of the most important championships.At the U.S. Open, Kyrgios beat the top seed and defending champion, Daniil Medvedev.Gabriela Bhaskar for The New York TimesFans cheered for Kyrgios at last year’s Australian Open.Alana Holmberg for The New York TimesWhether the tennis establishment likes it or not, no one in the sport fills a stadium like Kyrgios these days. Even his doubles matches have become raucous, packed affairs. And as the Australian Open gets underway, Kyrgios is among the favorites to challenge the nine-time champion Novak Djokovic for his home slam, which may be the ultimate double-edged sword. That level of pressure and expectation has been kryptonite for Kyrgios before, his self-destructive psyche exploding at a crucial moment, producing his unique brand of irresistible tennis theater.“It’s going to be a hard couple weeks, regardless of whether I win or lose, emotionally, mentally,” Kyrgios said in a pre-Christmas interview from his parents’ home. “I’m one of the players that has a scope lens on him all the time. Big target on my back.” With all his recent success and notoriety, so much suddenly appears to be riding on Kyrgios. The game’s leaders see him as the rare player who can reach a new and younger audience. Fans raise their beers and bump chests as Kyrgios wins points with his signature trick shots through the legs and behind the back. They wear basketball jerseys when they watch him and when they play, just as he does, and they turn his matches, even the doubles contests, into something like a rowdy night at a U.F.C. bout.“He brings something different,” said Andrea Gaudenzi, a former pro who is now the chairman of the A.T.P. Tour, which is the men’s professional circuit.Ken Solomon, chairman and chief executive of the Tennis Channel, the sport’s leading media partner, called Kyrgios “ground zero” in efforts to attract fans who have never touched a racket and perhaps never will. On Friday, Netflix released “Break Point,” its documentary series on pro tennis that the sport hopes will do for it what “Drive to Survive” did for Formula 1. The premiere episode focused almost exclusively on Kyrgios, who took a signature victory lap on Twitter.Tennis Australia announced last week that Kyrgios would play Djokovic in a charity exhibition Friday evening. Tickets sold out in 58 minutes.Before his exhibition match with Djokovic, Kyrgios hobnobbed with clients of a luxury hotel chain during a promotional table tennis game.Alana Holmberg for The New York TimesThree hours before the match, he hobnobbed with the top clients of a luxury hotel chain during a promotional table tennis game. Before the event started, he sat alone in a quiet hallway, feeling the pressure of what lay ahead. Moments later, holding a racket in a packed rooftop bar, the bright eyes and big smile of the star entertainer emerged.Leaning on Kyrgios as a pitchman for the game also carries plenty of risk. What makes him so irresistible, that at any time he might produce another can’t-miss moment on the court, has at times made him a walking grenade. And he’s the one with a finger on the pin.There is also the allegation of domestic violence.In early February, Kyrgios is due in court in Canberra to face a charge of common assault stemming from an altercation with an ex-girlfriend, Chiara Passari, in December 2021. Kyrgios has declined to discuss the matter since it became public during his run to the Wimbledon final in July.Common assault is the least serious assault charge in Australia, but it implies that the victim experienced immediate, unlawful violence, or the threat of it, though not bodily injury. Kyrgios’s lawyers have said they will mount a defense focused on mental illness, citing his history of depression and substance abuse, struggles Kyrgios has said will always be with him but that he now has under control. If the court accepts this defense and dismisses the case, it could then decide to impose a treatment plan. The maximum penalty for common assault is two years’ imprisonment.The incident occurred during the first weeks of Kyrgios’s relationship with his now constant companion, Costeen Hatzi, whom he met online. He had also just recommitted himself fully to tennis after years of ambivalence and mental turmoil. The sport had brought riches and fame but also loneliness, with its endless travel and solitary battles on the court, which tortured his psyche.Alana Holmberg for The New York TimesThe withering criticism and racist attacks he endured when he lost matches he was expected to win, or broke rackets and berated tennis officials, triggered memories of those years before a growth spurt at 17 turned him into a strapping, 6-foot-4 elite athlete. As an overweight boy with dark skin and modest means in an overwhelmingly white country where everyone seemed to have more, he was mocked and bullied, despite his talent for tennis, or maybe because of it.Goran Ivanisevic, the Wimbledon champion who coaches Djokovic, has called Kyrgios a “tennis genius.” Kyrgios’s father, Giorgos, first noticed that skill when Kyrgios was a toddler hitting a ball hanging on a string from a metal pole. He never missed. Soon Kyrgios was learning the sport on dilapidated courts near his parents’ home in Canberra. His father, a house painter from Greece, would hit a bucket of balls with him after work.“Still wears the same overalls he walked off the boat in,” Kyrgios said of his father, who still paints houses. “He must have been exhausted.”His mother, Norlaila, who is from Malaysia and worked as a software engineer for health care organizations, would drive for hours to get him and his brother to tournaments. They stayed at backpacker hostels and tried to stretch $20 to cover dinner for him and his siblings at cheap Indian restaurants in the countryside.His parents knew next to nothing about tennis. Tennis Australia and the tennis authority for his provincial region worked to fill in the gaps, and Kyrgios notched his breakthrough win at 19, when he upset Rafael Nadal at Wimbledon in 2014.Kyrgios’s breakthrough came at 19, when he beat Rafael Nadal in the fourth round at Wimbledon in 2014.via Getty ImagesIt nearly ruined him. After that win and all the expectations it produced, Kyrgios thought he had to solve every problem on his own. When he couldn’t, he lashed out, at tennis officials, the media and the people around him.Then, last fall, after a year in which he flirted with quitting but also showed flickers of his magical game, Kyrgios began to realize he didn’t have to do it all alone. He could talk about his fears and insecurities and the fragility of his mind to the people closest to him, and they could help.“Knowing that I am not alone anymore and I can kind of open up and talk to people, now that’s a big one for me,” he said. “It’s OK to, you know, feel like having to cry some days.”He also decided he was tired of letting himself and others down. Before last year’s Australian Open, he embarked on the kind of solid six-week training block he had not done in years. He played with top opponents for 90 minutes each day and hit the weight room. He spent two hours several times a week playing full-court basketball, his true love, with top Australian players to hone his conditioning.Asked for a scouting report on his hoops game, he put it like this:“Loves shooting mid-rangers.” “Can shoot a three-ball pretty good.” “Play like a wing.” “In the corner.” “Come off picks.” “Pretty versatile.” “Can guard a big.” “Pretty physical.” “Like Tobias Harris in his prime.”He also ate better, and he focused on getting more rest instead of more drinks.By the end of January, with Thanasi Kokkinakis, his countryman and childhood friend, he had won the doubles title for his first Grand Slam championship. Then he mostly stuck to the healthier living through Wimbledon, where he once had to be dragged from a pub at 4 a.m. on the morning of a match. Not this time, though his sublime tennis did come with multiple confrontations with chair umpires and a tense verbal-sparring match with Stefanos Tsitsipas, during which Tsitsipas tried to hit Kyrgios with a ball.Kyrgios won the Australian Open men’s doubles title last year with his friend Thanasi Kokkinakis.Alana Holmberg for The New York TimesKyrgios had a few confrontations with chair umpires at Wimbledon this year but reached his first Grand Slam singles final there.Hannah Mckay/ReutersHe fell to Djokovic in the final in four sets, but he remained disciplined through the U.S. Open. There, he obliterated the top seed and defending champion, Daniil Medvedev, in the fourth round before suffering an upset loss to Karen Khachanov of Russia in the quarterfinals. Exhausted from the season and from playing mostly at night so broadcasters could maximize the television audience, he caught the first flight home and played just one more singles tournament.Kyrgios will play Roman Safiullin, an unheralded Russian, in the first round Tuesday.What happens now?Tennis, like few other sports, is an M.R.I. of the soul. Kyrgios knows he will never pursue the game with the clinical efficiency and emotional discipline that Nadal and Djokovic have showcased for so long. He is going to throw and break rackets. It’s a manifestation of how much he cares, he said, and for him to thrive, tennis has to be about who he is, someone who plays with emotion, instinct and improvisation, like a jazz solo rather than a symphony.If he can do that, maybe he can find peace on the court, even when the pressure brings the stress of a near-explosion that keeps his mother, too worried about what will happen, from being able to watch.“Not many people can say that they have become a Slam threat, they are going to have the support of the nation, well, the support of some of the nation behind him,” he said. “Just got to try to enjoy it.”For Kyrgios, that has always been the toughest task of all. More