Like many English cricket fans, I first became properly aware of Shane Warne when he ran up to bowl to Mike Gatting in the first Test of the 1993 Ashes series at Old Trafford. It was his first ball in a Test match against England. Tanned, podgy and with bleached blonde hair, he looked more like a Home and Away actor gone to seed than a spin bowler. From a few paces, he sent down a ball that appeared to be drifting inno cuously towards Gatting's pads. Upon landing, however, it turned and bounced viciously, and before Gatting could adjust his shot it had clipped his off bail. Gatting stood rooted to the spot, seemingly unprepared to believe what had happened. Spin bowling - and indeed Test cricket - would never be the same again.

The "Ball of the Century", as it became known, set Shane Warne on the path to becoming the all-time greatest Test wicket-taker (he has taken 685) and inspiring Australia to countless wins. He has ripped through the batting line-ups of most countries; only against India has he consistently failed to excel. What's more, in achieving this, he has helped revolutionise cricket. Spin bowling - and leg-spin bowling especially - was a moribund art when Warne appeared on the scene. Over the previous two decades, the West Indies had dominated cricket by assailing batsmen with an unvarying barrage of pace. Other countries inevitably sought to imitate them, and spinners became deployed more as defensive fill-ins than as strike bowlers.

Warne changed all that. With his ability to turn the ball prodigiously and his bamboozling array of variations - the flipper, the slider, the googly - here was a spinner more aggressive than any fast bowler. And where Warne led, others followed. Today, many of the most feared bowlers are spinners. Warne's great rival is Sri Lanka's Muttiah Muralitharan, he of the crooked arm, who has an even better Test average than Warne and who looks certain to overtake his wicket-taking record. Over the same period, India has had Anil Kumble and Harbhajan Singh, Pakistan Mushtaq Ahmed and Danish Kaneria. Even England has recently unearthed a slow bowler of quality in Monty Panesar.

And it's not just bowling that Warne has revitalised. The spin renaissance has arguably been the main factor in the rise of a new kind of ultra-aggressive batting, which in recent years has helped turn Test cricket into such an exciting spectacle. Batsmen have discovered that the only way to counter a bowler such as Warne is to dominate him. If you try and defend, you'll score few runs - Warne is unerringly accurate - and will eventually lose your wicket. The contest between the attacking spinner and the equally aggressive batsman is now at the heart of Test cricket. At its best, such a contest is enthralling - as was the case last summer whenever Warne bowled to his friend and Hampshire team-mate Kevin Pietersen.

On the pitch, Warne may be canny, skilful and generally well behaved, but off it, as Paul Barry makes clear in his entertaining and shamelessly sensationalising biography, he is less of a paragon. Warne was implicated in the match-fixing scandals of the late 1990s and is the only leading cricketer to have been banned for drug-taking. (In 2003 he received a year's suspension for taking a diuretic or dieting pill.) But it is his persistent infidelities - Warne has been married since 1995 - that have attracted the most attention. The charitable view of Warne is that he is a "larrikin" - the Aussie word for someone who likes a good time. But as Barry tells it, the reality is more sordid. The pattern for Warne's approach to sexual conquest was set in 1990 when, according to the author, he approached three Asian women at a swimming pool in Darwin, parted his dressing gown and said: "Hey girls, how d'ya like to suck on this?" Warne's standard tactic when he meets a woman he likes is to obtain her phone number and then bombard her with calls and explicit text-messages. Tabloid kiss-and-tell stories have accompanied him throughout his career. Remarkably, his wife stood loyally by him for a decade, until one lurid exposé too many finally prompted her to leave him last summer.

Still, it seems unlikely that Warne's misdemeanours will do his reputation any real harm. Cricket is an astonishingly sexist game - probably more so than football - and is rife at every level with admiring tales of drunken off-field ex- ploits. Cricket fans are prepared to forgive their heroes virtually anything. Warne is little different, in essence, from other cricketers - just that bit more extreme. He will go down as a legend in more ways than one.