The Rocket is set to fire this time

Ronnie O'Sullivan is calm. The Rocket is ready. In place of the smouldering wreck described in his more hysterical press clippings, Ronnie the Rocket looks cool and thoughtful as he considers the story of his life so far. It is a strange and wild tale. One day it might belong as much on the big wide screen as it does clicking softly inside his crowded head with the sound of one coloured ball rolling into another.

The way he tells it, the Ronnie O'Sullivan story has a title. There is only one problem. Arthur Miller has already written The Crucible. Even Ronnie does not know anyone sharp enough to find a way round that one. But it still names the place where he has experienced such extreme emotion that people imagine he is either a fleeting "genius" or the perennial "bad boy" of British sport. The truth is more interesting.

The Crucible theatre in Sheffield is the hushed site of his most searing ambition. Tomorrow he begins his latest pursuit of a world championship which, in terms of pure talent, he might have already won three times. But this is something harder than a sentimental reworking of Jimmy White's saga of glorious failure.

Three years ago at the Crucible O'Sullivan turned a piece of wood measuring 58 inches and weighing 18 ounces into a magical sporting wand. In the midst of another world championship first-round match he picked up his cue and emptied a dazzling green table with 36 breathtaking shots.

Apart from making him only the fourth player in world championship history to score a maximum break of 147, O'Sullivan racked up his clearance in a record five minutes and 20 seconds. He earned a television bonus of Stg£165,000 which made his break worth £515 a second.

The photographs which later captured his rapture as he peeled back the wads of cash spoke of a feeling deeper than greed. He looked like a man who had found release from some terrible demons - the kind which a year before saw him punch Mike Ganley, an assistant press officer at the Crucible. A suspended two-year ban from the game was slapped on him.

But even that memory was nowhere near as distressing as the moment when, on the day he had qualified for his first world championship in 1992, O'Sullivan heard that his father had been sentenced to life imprisonment for murder. He was acknowledged as the most gifted young player the game had ever seen but, on the inside, a 16year-old boy felt lost.

O'Sullivan's subsequent depression was not eased either by the brief jailing of his mother, Maria, for VAT evasion or his own public struggles. "I've had a lot on my plate," he said in 1994. "Life's been a bitch." His finest performances were often overshadowed by spats with fellow players. He even failed a drugs test when traces of cannabis were found in his system after he won the Irish Masters in March 1998.

The roller coaster continues. Before demolishing the world number one Mark Williams to win the Scottish Open final 9-1 last Sunday O'Sullivan had skidded through the tournament. In a typical encounter against Quinten Hann he achieved the second fastest 147 in history - his six minutes and 40 seconds maximum looking leisurely compared to that Crucible whirlwind. But O'Sullivan blew his 4-0 lead and just squeezed home in the deciding ninth.

"I'd have topped myself if I'd lost," he said. "I was so frustrated it was frightening." He now sounds more sanguine. "I won five deciding-frame matches," he murmurs. "A year ago I might've lost one of them. That has to stand me in good stead for Sheffield. My attitude in the final was brilliant. I thought `yeah, days like these are what I've practised my whole life for'. I know I'm tough to beat. I've won enough tournaments to prove I can perform under pressure. It's just a case of keeping my mind in gear."

O'Sullivan finally appears ready to sustain the equilibrium which has so often deserted him. He is also incisive enough to explain why his match psychology sometimes falters. "I find it difficult to sit in the chair and watch my opponent. I get frustrated because I can immediately see the shot that needs to be played. The other guy might look around for ages before he settles on that same shot. They make such hard work of it. I could have made a 30 or 40 break in that time but suddenly I get anxious that he might shut me out of it."

"People get the wrong impression. They think: `Lucky old Ronnie - he's got all the talent in the world.' But I work hard. That's why Tiger Woods is an inspiration. Golf might come easy but he has mental toughness. Part of that is learning to block everything out."