You could hardly call Thomas Muster a regular on the London scene. In a tennis career spanning 15 years the Austrian left-hander opted to play Wimbledon only four times, and never once walked off the lawns of SW19 a winner. So Thomas has been enjoying his involvement with the Masters tournament at the Albert Hall, marching through to this afternoon's final, enjoying incognito runs in Hyde Park and indulging in a spot of sightseeing.

You could hardly call Thomas Muster a regular on the London scene. In a tennis career spanning 15 years the Austrian left-hander opted to play Wimbledon only four times, and never once walked off the lawns of SW19 a winner. So Thomas has been enjoying his involvement with the Masters tournament at the Albert Hall, marching through to this afternoon's final, enjoying incognito runs in Hyde Park and indulging in a spot of sightseeing.

Muster has, though, caused a stir or two in the old town. In 1996, the year when he rose to world No 1, he turned up at the Stella Artois tournament at Queen's Club, and it needed all Stefan Edberg's grass-court skills to keep him from a place in the final.

However, he made bigger headlines, and on the front pages, too, over his friendship with Sarah Ferguson, Duchess of York. As he puts it: "I achieved something that the guys who actually won Wimbledon never managed. I featured in stories on the front pages of British newspapers without ever appearing on the back."

Now, after tiptoeing away from tennis in 1999, abandoning Monte Carlo for Queensland and immersing himself so thoroughly in the Aussie lifestyle that he piled on nearly four stones in extra weight, Muster is back in Austria, a failed marriage behind him, captaining his country's Davis Cup team, heading an ambitious development programme for juniors and making a big impact on the senior circuit, the Delta Tour of Champions. Muster had intended to take up a two-year contract as Davis Cup captain in time for the 2005 competition, but when the incumbent, Gunther Bresnik, resigned in the wake of a 5-0 defeat by the United States in February, the man who won 36 of his 44 Cup singles agreed to step in early, and led the squad to victory in the World Group play-off against Britain in Portschach at the end of September. With his 37th birthday coming up a week later, the Iron Man resisted all sentimental calls to form part of the Austrian doubles team.

The Iron Man description prompted a small smile as Muster relaxed in the players' lounge at the Albert Hall. Opponents, he said, were always so preoccupied with his super-fit reputation that they underestimated his racket skills.

"Everyone kept saying I was so fit, but you don't win the French Open and get to No 1 if all you have is fitness. I used that to my advantage. A lot of people said, 'How can I lose to this guy? He can only run'. But I have won tournaments indoors, played all right on grass at Queen's and done pretty well on hard courts."

That said, all but four of his 44 tournament wins came on clay, where he was for a time simply invulnerable. The highlight, his lone Grand Slam victory in the 1995 French Open, climaxed a run of 40 successive wins on clay.

As someone who set up residence in Monte Carlo at the age of 18 in order to get regular practice there against the then superior talents of Bjorn Borg, Boris Becker and Mats Wilander, Muster found his finely honed condition an ally following a horrendous accident on the first day of April 1989.

Having just reached the final of the Miami tournament, Thomas was unloading his tennis bag from a courtesy-car boot when the vehicle was slammed into by a drunk driver. Doctors told him the severed knee ligaments he suffered would keep him out for a year, but he was back five-and-a-half months later. "It's incredible what the mind and body can do," he said. "But I don't think I could do it today."

Muster's single-mindedness was also evident in his decision, at the start of 1999, to retire at the French Open. "But I didn't tell anyone because I didn't want ceremonies everywhere I played. I didn't want to be asked at every tournament why I was quitting and what I was going to do. So I just walked away after losing to [Nicolas] Lapentti in the first round at Roland Garros.

"When I started my career there was no one there and when I stopped no one was there, either. It was my favourite tournament and I knew it was my last match. Those are big moments, and I didn't feel like sharing them with anyone else."

Three months later, having decided he did not fancy a return, Muster threw away all his tennis gear. "I had no further interest." He headed for the good life in the Queensland resort of Noosa Heads, where he had bought property six years earlier. He got married, fathered a son, showed off his pilot's licence in two helicopters he had acquired, drank beer, sat around and watched his weight soar from 11st 10lb to 14st 7 lb. "I didn't really care," he said. "I didn't want to exercise, because that was what I had done all my life. When I decided to get fit again it took me six months to get all that extra weight off."

Now, with his decision to boost the quality of the seniors' circuit, the fitness lifestyle has been reclaimed. Having collected in excess of $12m (£6.2m) in prize money alone, Muster can afford his gesture of working for nothing as Davis Cup captain and also donating his time to develop the Austrian junior programme at a new centre in Graz, where he now lives. The helicopters, however, have been sold. Flying around is confined to the tennis court again these days.