Austria's first superstar of the tennis courts, probably the most courageous and fiercely competitive player there is, remains an unknown warrior at the All England Club.
It was understandable, therefore, that Muster's cry of "Ja!" in Johannesburg yesterday should carry far and wide. He was celebrating the first grass- court victory of his professional career, 6-2, 7-6, 6-2, against Marcos Ondruska, of South Africa, in the opening rubber of the Davis Cup. "I'm somebody who always tries to learn," Muster said.
The left-hander's four visits to Wimbledon's lawns have resulted in three straight-sets defeats, by Guy Forget (1987), Grant Stafford (1992) and Olivier Delaitre (1993), and one in five sets, by Alexander Mronz (1994) - a unique occasion when Muster actually had a match point.
On Monday, none the less, Muster will become the 13th world No 1, joining an exclusive club whose membership has ranged from Ilie Nastase to Andre Agassi since the ATP rankings system was introduced in 1973.
The thing is, Muster performs predominantly on clay courts - of his 35 singles titles, one was accomplished on rubberised concrete and another on an indoor carpet - and he is the first player to elevate himself to No 1 after spending the majority of his time on the sport's slowest surface.
Embarrassed by his Wimbledon record, however, the 28-year-old French Open champion has decided to address the situation before it is too late. "I've won in Paris, and I've had major records on clay, and now I'm becoming the No 1 player I'm looking for other goals. I want to prove - not to others, but to myself - that I can also play well on grass. It's a major motivation for me, actually," he said.
This summer he intends to play two grass-court events during the fortnight between the French Open and Wimbledon: at London's Queen's Club (or Rosmalen, in the Netherlands), and Halle, in Germany.
He may not be a man for all seasons, or for all tastes, but surely not even those who quaintly persist in using the term lawn tennis for a sport played on a variety of surfaces - grass least of all - would dismiss Muster's ranking as a blip on the computer.
Lucky 13? Admittedly, it would have been more satisfactory had he reached the summit with a swish of his racket rather than a switch in the tournament scheduling to accommodate the Davis Cup ties. That has resulted in Muster's rivals losing points before they had a chance to defend them, promoting the Austrian a mere nine points above Pete Sampras and 95 ahead of Agassi.
But who would be so curmudgeonly as to deny Muster a helping hand to the peak, bearing in mind the fortitude with which he has scaled the mountain? This is the man, remember, who in 1989 made an astonishing recovery from an accident that would have ended many another's career.
It occurred at a time when he was enjoying particular success on the concrete courts, having followed up an appearance in the semi-finals of the Australian Open by defeating Yannick Noah to reach the final of the Lipton championships in Key Biscayne, Florida.
The final, against Ivan Lendl, did not take place. Only hours after the victory against Noah, Muster was lifting his bag from the boot of a car in Miami when the vehicle was struck head-on by a drunk driver and rolled over him, severing ligaments in his left knee.
Shortly after undergoing surgery in Vienna, Muster was at work on the practice court, aided by a contraption which enabled him to swivel and hit balls while laying on his back with the injured leg immobilised.
Less than six months later, Muster returned to the tour, grunting and pulverising as energetically as ever, though advised by doctors to play on the softer surfaces to minimise stress on the knee. "But sooner or later I had to take the risk and go back on hard courts to improve my ranking and become a more complete player, even though it's more painful.''
Muster may not be pretty to watch, but the intensity with which he goes about his work can be mesmerising. Although on the short side for the modern game, at 5ft 11in, he is regarded by many of those who have been tortured by his topspin as something of a monster, unrelenting in his determination to grind them into the court - and often fresh enough to do press-ups in the locker room afterwards.
Boris Becker was fined $20,000 (pounds 13,000) by the ATP Tour last year after insinuating that something other than toughness inspired Muster's comeback from dehydration after the semi-finals of the Monte Carlo Open to beat the German in the final. "Either he is a very good actor, or something miraculous happened overnight, and I don't believe in miracles," Becker said.
For Muster, winning the French Open last June, his first Grand Slam title, was the fulfilment of his boyhood dreams. October brought the bonus of a first triumph on an indoor carpet court to add to his 11 clay-court titles during the year (including a winning sequence of 40 consecutive matches on clay).
"I think I deserve to be there [No 1] for the way I played in 1995, whichever ranking system would have been available at that time," he said. "To say I achieved No 1 by playing on clay is not quite true. I won the biggest indoor event last year in Essen, and I did beat Pete Sampras there, indoors, which is a big achievement for me. So nobody really can say that I only can play on clay. I had good results on hard courts. I made more points on hard courts than Pete made on clay, for example.''
Moreover, he had a 12-0 record against top-10 players prior to November's ATP Tour Championship on a carpet court in Frankfurt, where he took Michael Chang, Jim Courier and Thomas Enqvist the distance before losing his three round-robin matches.
"It's not that you can buy your points in the supermarket and say `I want to be No 1'," Muster said. "Maybe grass is not a surface which suits me perfectly, but I think I can be dangerous on all other surfaces.
"There are probably a lot of clay-court tournaments, but the majority of big tournaments are still indoors and on hard courts, and I think that hard-court players have much more of a chance to become the No 1. Three Slams out of the four are played on a fast surface, and you really have to win all the major events on clay to get a chance to become No 1.''
Which is precisely what Muster did in becoming the second oldest No 1 (John Newcombe was 30) and the third left-hander after Jimmy Connors and John McEnroe.
It is the first time that three players have been No 1 in the same year since 1983 (Connors, McEnroe and Lendl), and Muster breaks an American monopoly (Jim Courier, Sampras and Agassi) which has lasted for the 175 weeks since Stefan Edberg, of Sweden, was at the top in September, 1992.
Even if it should transpire that Muster is king for only a week, he can take inspiration from thoughts of finally making his presence felt at the world's most prestigious championships. "But that doesn't mean I will plant grass in my living room.''