Where he exists, success and failure are relative. This is someone who has racked up 17 victories in the past two and a half years, who elbowed Tiger Woods out of the world number one spot, and who in 2004 won a staggering nine events on the fiercely competitive PGA Tour.

Broadcasting companies in the USA might not have liked that their posters boys, Woods and Phil Mickelson, were being eclipsed by someone who was sullen, sometimes monosyllabic and whose most telling chip was on his shoulder. Singh, with that kiss-my-ass attitude about him, and with his relentless practice regime, looked as if nothing could stop him. The serial winner was here to stay, and then suddenly, maybe he wasn't.

Such dominance . . . Lee Westwood, usually a master of understatement, called his 2004 season a "miracle" . . . has been put into stark relief by his current form. Singh has now gone a total of 21 tournaments, and nine months, without a win. If most certainly not a slump of Duvalesque proportions, the magic, it appears, has evaporated.

Not too many people have used the 's' word within his earshot, but a month ago at the high-profile Players Championship at his home base of Ponte Vedra Beach in north Florida, Singh offered some class of an explanation for this barren period. "It's not because I'm not playing well, I'm just not playing the way I did last year and the year before. My level of play has dropped, not just out of neglect or anything. That's just the way it goes, I mean, golf is a weird game."

But the belief was that the 43-year-old Fijian had gone closer than anyone bar Woods to removing the grey area of chance from the game. His monastic formula of pounding hundreds and hundreds of balls in the waking hours, allied to intensive gym work, brought him level with, and then past, Woods. For a time, it seemed that Singh wanted it more than his main rival.

While it is hard to conceive that his desire has dried up, it could be possible that by his own rarified standards, he is a fading force. Poised for victory at the Players Championship, he dropped like a stone with a 77 in the final round, and then there was a broad hint of a return to that once imperious form when he opened with a 67 at Augusta. He would eventually finish in the top-10 but such was his discomfort on the greens, that he never emerged as a threat to Mickelson.

More recently he blew an opportunity at the Houston Open, an event he had won twice in succession, with a 75 in the third round. "I'm just not playing well enough to win, " he admitted, "there are too many mistakes."

If Singh bristles at any suggestion that he is in a slump, he will no doubt remember the constant questioning that dogged Woods when he was overhauling his swing with Hank Haney. In 2004, with Singh in the middle of his annus mirabilis, Woods failed to win a stroke-play event in the US, and he also had to endure a run of 10 major championships without success before last year's Masters victory.

Logically, Woods and Singh should be mentioned in the same breath as golf 's two alpha-players in the past six years, but Singh has grown weary of the comparisons.

He felt that his achievements in 2004 were somehow downgraded when they were invariably set against Woods's benchmark 2000 season.

While Singh won nine tournaments including the USPGA at Whistling Straits, Woods's 10 wins worldwide included the US Open, the British Open and the USPGA titles. More significantly, Woods won the US Open at Pebble Beach by a staggering 15 shots, and the British Open at St Andrews . . . where for the first time in the history of the event, the Claret Jug engraver began work before the winner completed his final round . . . by eight shots.

Where there was once a reasoned debate over the merits of the two seasons, the argument has now come down to a single question: can anyone remember who won the one major title that eluded Tiger Woods in 2000?

Vijay Singh, the Masters.

The theory that the Fijian's current frustration is all down to putting woes is far from watertight. He is in fact 15th in the PGA Tour list with an average of just under 29 putts per round, yet if anything, the belief that his unease on lightning fast greens will rule him out of a fourth major championship victory has strengthened of late.

Unlike Woods when he struggled to win, Singh is not in the throes of any technical change, and unlike Woods, who has recently married and whose father is critically ill, there have been no significant shifts in his personal life, so it could be that Singh has for some reason lost the swing that once repeated itself with such metronomic precision.

He concluded at the Players Championship that he was struggling to find his rhythm, but the countless hours on the range have since failed to solve the problem.

"Hopefully, I can just take it out there and play now and not think about what's wrong with my golf swing, " he said last month.

However, history has shown that most slumps, whether they be monumental in the cases of former major winners, Ian Baker-Finch and David Duval, or relative in Singh's case, are inevitably more psychological than anything else. After Baker-Finch triumphed at the British Open in 1991 going out in a sublime 29 at Birkdale in the final round, it appeared that he was destined for even greater things, but eight years on, he had lost his game completely and would card a 92 at Troon in the same championship.

Duval's "is that all there is?" remark in the aftermath of his British Open victory at Lytham in 2001 was an indication of the complexities of a player who had been world number one, who had strived for major success, but who couldn't fathom what the journey had been all about when he reached his destination.

He would win another tournament that year, but eventually decided to quit the game for the best part of a season as his confidence drained away. Duval returned to play 20 events last year, but only made a single cut.

For different reasons, Seve Ballesteros and Sandy Lyle were among the world's best players who fell from grace, while more recently, Westwood has had to work his way back from a two-year slump. A winner six times in 2000, and by some margin the best player in Europe, Westwood summed up his predicament succinctly: "One minute I'm on top of the world, the next I'm wondering if I'll ever make another par."

So even if Singh has spoken about a swing that has slipped out of sync, it is more likely that he is less mentally sharp, less driven than before. Asked about his demanding schedule once, he said it was no big deal. "We fly in private jets, we're really spoiled, so I don't understand why you would be tired if you only played 18 events. And if you play 30, that's still 22 weeks off every year."

Yet, this season, he has opted out of five tournaments in America including this week's Zurich Classic in New Orleans, yet he travelled to Abu Dhabi and Qatar . . . where appearance money was probably part of the allure . . . for two European Tour events.

"That was a real bad move, " he admitted. "I think I wasted three weeks."

Years ago he explained that what separated him from the rest was that he was prepared to do whatever it took to succeed. "I did that from a young age, " he added, "and it gave me toughness." That toughness is now under question as he strives to rediscover the heights of before.

He remains a highly relevant factor in the equation at the top of the world game, but it could be that Vijay Singh's time has come and gone.