VIENNA: Former Austrian tennis ace Thomas Muster said he was surprised by Andre Agassi's recent drug revelations but that they did not "in any way" diminish his achievements, in an interview published Sunday.

"I was surprised he admitted to doping after such a long time," Muster, who faced the American on several occasions during his career, told the Austria Press Agency (APA) on the sidelines of the ATP tournament in Vienna.

"I don't understand how one would want to damage one's image in a book like that after such a long time," he added.

Agassi, one of just six men to have won all four Grand Slam titles and widely regarded as one of the sport's finest players, revealed in a new autobiography that he took crystal methamphetamine in 1997 when his form was falling and also lied to sporting authorities to escape a ban.

For Muster, this did not "in any way" diminish Agassi's achievements in tennis.

"He was a very fair athlete, a colourful character at the beginning who then developed into a gentleman," Muster said, insisting that Agassi's career was not a lie.

But he admitted: "Following the comments by Andre Agassi, certain things that people used to whisper about have become a lot clearer."

Doping was not a major problem in tennis, the Austrian noted however.

"Tennis isn't really a doping sport, it happens rather rarely."

"Obviously there have been cases, and some people have been handed bans for that, but it isn't common practice in tennis to dope yourself," he said.

Revelations that Agassi had worn a hair piece to hide his baldness were also nothing new, said Muster.

"It was well known that his hair wasn't real!," he said. "But it wasn't discussed at length."