O’Sullivan “sits over everyone,” an ex-manager said. “He is not a normal bloke.” Photograph by Nadav Kander

Early on a Tuesday morning last fall, Ronnie O’Sullivan was running through the woods near his home, in Chigwell, Essex, northeast of London. It was damp and muddy, England in November. O’Sullivan, who is thirty-nine, loves the anonymity of running. About ten years ago, he discovered that it was one thing that truly takes him out of himself—more than the drink and the drugs and the antidepressants—and suspends the otherwise unavoidable fact that he is the most talented snooker player of all time. At the age of eleven, O’Sullivan was making good money in the sport, and in the past three decades he has won five World Championships and set a number of records while enduring a bewildering odyssey of breakdowns, addictions, and redemptions, largely precipitated by the imprisonment of his father, whom he loves, for murder. O’Sullivan is frequently described as a genius. But he does not see how this can be so. Most days, he feels like a fraud. His game comes only in fits and starts. He wins because the others lose. He has wondered for a long time whether he would be happier doing something else. He has moved nine times in the past ten years. “I’m fucking, you know, searching,” he told me recently. “I kind of know who I am but I don’t like who I am, do you know what I mean? I wish I was a bit more fucking stable.”

O’Sullivan tries to run six or seven miles a day. That morning, he was with his best friend from school, George Palacaros. (O’Sullivan grew up a short distance from Chigwell, in the town of Ilford.) It was a final run before the U.K. Championship, snooker’s second-biggest tournament, in York, two hundred miles to the north. O’Sullivan’s first-round match, against an amateur named Daniel Wells, was two days away. About five miles into the run, Palacaros called out to O’Sullivan to check the heart-rate monitor that he wears on his wrist. As O’Sullivan turned to reply, he slipped and fell, breaking his left ankle.

He tried to carry on. “I thought, I ain’t going to waddle back,” he said. He jogged another mile, but whenever he looked down he saw his ankle swelling up. By the time O’Sullivan reached the changing room at his running club, he couldn’t put any weight on his leg.

At the hospital, O’Sullivan was told that he had a simple fracture. His ankle wouldn’t need surgery, but it would take twelve weeks to heal and he would have to wear a protective brace. He called his psychiatrist. In the afternoon, O’Sullivan posted a picture of his ankle, bulging alarmingly, on Twitter, with the message “Might be one legged Snooker at the #UKChampionship on Thursday.” He found a pair of soft blue boots in his closet that fit over the brace. The next day, a friend drove him to York so that he could keep his foot elevated on the way.

Snooker, like its poor relation pool, is a cue sport. Unlike pool, snooker has twenty-two balls: fifteen red, six of other colors, and one white. (Pool and its variants involve sixteen balls or fewer.) Players take turns attempting to clear the table and earn as many points as possible, using the white cue ball to “pot” a red, then a colored ball (which is returned to the table), then a red, and so on. When all the reds are gone, the players dispatch the colors in order of their value, from the yellow, which is worth two points, up to the black, which is worth seven. If a player fails to pot a ball at any point, he must yield the table to his opponent. Matches are divided into frames, each won by whichever player scores the most points. In the professional game, frames tend to unfold with vivid, unsettling ease—the balls slide into the pockets as if there were nowhere else for them to go—or with staggering, metaphysical difficulty, as the players foil one another by arranging the balls in illogical patterns, a type of play known as “safety,” and everyone’s nerves go to hell.

Snooker’s civilized appearance belies its vicious and enervating nature. A snooker table is three times larger than a pool table and its pockets are an inch smaller. Even the most basic shot is a concatenation of foresight, friction, and various Newtonian laws. Players seek to control where at least two balls are going: the red or colored “object” ball, preferably toward a pocket; and the white ball, its rate of braking and spin carefully calibrated, either to stop near another object ball, so the process can begin again, or to continue toward some hostile district of the table, from where the opponent will be unlikely to score. The best players string together thirty shots in a row, in a hushed environment of thick carpet and dinner suits. (Snooker’s dress code recalls, more or less, that of a nineteen-thirties music hall.) Players compete to pot the same balls, so every shot has a psychological echo: What is good for me is bad for you. The longer I am at the table, the longer you must watch and fret. Players avoid eye contact. No one speaks.

At the U.K. Championship, all matches except the final were the best of eleven frames. O’Sullivan was reluctant to put weight on his ankle. “I feel like a baby that’s trying to learn to walk,” he told reporters. He limped through his first match but won, 6–2. Three days later, in the second round, he faced Peter Lines, a forty-four-year-old journeyman pro. I travelled north to watch him play. I reached the Barbican theatre in York, just outside the city’s medieval walls, early in the evening.

O’Sullivan had been debating whether to pull out of the tournament. His balance wasn’t right. There was no sign of him by the practice table, where the other players, dressed in bow ties and waistcoats, waited, leaning on their cues. Referees pulled on white gloves. Nevertheless, at 7 P.M., O’Sullivan appeared, walking out under the lights in answer to the snookering nickname that he has had since he was a teen-ager, “Ronnie (the Rocket) O’Sullivan!” In a dinner suit and his blue boots, his sideburns shot with gray, he looked like a croupier on his way home from work.

“You don’t feel comfortable when Ronnie’s playing,” Barry Hearn told me. Hearn has been snooker’s dominant impresario since the nineteen-eighties. He controls the commercial rights to the sport and has managed O’Sullivan three times, on and off, throughout his turbulent career. (O’Sullivan fired two managers during the reporting of this article.) “You’re almost watching an accident waiting to happen,” Hearn said. Against Lines, O’Sullivan was obviously out of sorts. Most snooker players, obsessed with repetition, seek to become robotic versions of themselves. But O’Sullivan in full flow is always in motion, checking this, squinting at that, buzzing backward and forward around the table, grimacing at the balls, fussing at chalk marks on the baize. His ankle made that impossible. Every movement was an effort.

Still, it was too much for Lines. Ranked sixty-first in the world, he seemed unnerved by the television cameras and missed a number of easy shots. Many lower-ranked players find it hard to concentrate when they play O’Sullivan. The crowd is against them, and they wonder what he thinks of their game. The match was untidy. In the fifth frame, with the score at 3–1, O’Sullivan potted a fluky red and the balls suddenly opened. In the course of twenty-nine strokes, he scored a hundred and six points—a “century”—and it seemed as if he might race away. But Lines came back. O’Sullivan was distracted; he picked his teeth and watched the game under way at a nearby table. “Come on, Ronnie, our son,” a Yorkshire voice called out from the crowd. By the time the game finished—6–3, to O’Sullivan—it was ten-thirty. O’Sullivan was exhausted. I caught up with him in the corridor as he hobbled back to his dressing room. In person, he can be disarming—trouble, but you want him to like you. I congratulated him on the match and said I enjoyed it. “Fucking hell,” he said. “I didn’t.”