IT HAS taken him five years, but today Phil Mickelson is a much shallower, and more successful professional golfer, than ever before. He also has less fun, about which more later.

Mickelson is the prodigy before last, the one before Tiger Woods, the one who, at the age of 26, has made it all the way to the top of the US money list, which he currently leads with over $1.5 million. Last week he led his country to victory in the Dunhill attempts to win the Toyota World Matchplay championship at Wentworth for the first time, starting today with a match against Vijay Singh.

Mickelson has known nothing but golf all his life.

He began at the age of two, apeing his father and becoming a left hander not because he is lefthanded but because he got a mirror image of the parental swing. He became exceptionally good very quickly indeed, and, making all the stops along the way, won everything that amateur golf had to offer.

That included not only three NCAA championships, but one of them in the same year, 1990, that he won the US Amateur, becoming the first golfer since, yes, Jack Nicklaus, to do that particular double.

Mickelson was a phenomenon. He best rode amateur golf fairways with a smiling arrogance, born of total confidence. When he won a US Tour event, the Northern Telecom Open, as an amateur, he demonstrated just what a resilient player he was. As the tournament reached its climax, Mickelson took a triple bogey seven at the 14th, to barely stifled cries of "He's choked". He then hirdied two of the last three holes, and his principal challenger, veteran Tom Purtzer, took two in a hunker at the 18th to be the final, losing choker.

When he came to Portmarnock to play in the Walker Cup in 199 he was a natural choice to play in the first match, and he hit the opening blow, a huge drive down the middle. He stared after it for longer than is normal, relishing his position as the centre of attention on that elevated tee, and then, when he broke his pose, flipped his driver some 10 yards through the air to his waiting caddie. It seemed like a "follow that" gesture, a challenge, and it was the mark of a supremely confident person.

Earlier that year he had been playing in the Golf Digest Collegiate Invitational against Manny Zerman, whom he had beaten in the final of the US Amateur. Mickelson had alienated Zerman, and so when he asked for a free drop from what he alleged was casual water, Zerman refused.

There was mud on the ball and Mickelson, after staring hard at his man, took a seven iron and, with an exaggerated out to in swing to avoid the dirt, hit a 160 yard shot, over a lake, straight into the hole for the first ever eagle two made at that hole. Zerman's coach saw the incident and told his man: "The next time Phil wants a drop, give it to him. Don't make him mad."

Mickelson became famous, notorious even, for his ability to produce seemingly impossible shots. Faced with a lake, he would sometimes deliberately "Barnes Wallis" his ball over it, bouncing it up onto the green. Occasionally, as if for the hell of it, when he missed a green and finished on an upslope, he would face away from the pin and hit the ball so hard with an opened up wedge that it flew back over his shoulder onto the putting surface.

There was the joyousness of youth in all this, and when he first turned professional he was a revelation in the way that he would interact with the spectators. He would chat and joke with them between green and tee, sign autographs, pose for pictures. "It won't last," said the old pros, and they were right.

"It's sad, really," said Mickelson yesterday. "The fans became so forward and so abrupt with their demands that I had to change. It wasn't by choice. Golf is one of the few games where player and public can get real close, but now you can't talk to family or friends without someone; sticking a pen and paper in front of your face."

If some of the fun has gone from the game, Mickelson is sombre all the way to the bank. Last year the man with the most educated hands in the game decided that to become a more complete golfer he had to stop the overswing, the dip past parallel at the top of the backswing, that was such an obvious feature of his golf.

"I did it myself," said Mickelson. "I worked out a way of swinging shorter without losing power, and it involves a shallower plane. I used to pick the club up too steeply, which meant hitting down on the ball too sharply and the ball would fly too high. It was not a good swing in a wind, but now I'm a whole lot more consistent."

If the weather forecast for Wentworth is correct, that swing change will serve him well, for this week and the foreseeable future.