Tennis champion Andre Agassi's admission of drug use more than a decade ago has caused confusion and condemnation among current and former tennis pros, including some who have been professed admirers of his career.

In his forthcoming autobiography, Agassi admits that he once used crystal methamphetamine in 1997, during a low point in his personal and professional life. "There is a moment of regret, followed by vast sadness," said Agassi in describing the experience of using the drug. "Then comes a tidal wave of euphoria that sweeps away every negative thought in my head. I've never felt so alive, so hopeful -- and I've never felt such energy."

Later, when an ATP drug test came back positive for use of the recreational drug, Agassi lied to tennis officials, saying he ingested the drug accidentally, Reuters reported Oct. 28. "I feel ashamed, of course. I promise myself that this lie is the end of it," Agassi recalled. Agassi was never punished for drug use during his career.

The Australian reported Oct. 31 that reaction from the tennis world was mixed, with fellow Hall of Fame player Martina Navatralova offering an especially harsh assessment.

"It's not as much shock that he did it as shock he lied about it and didn't own up to it," said Navatralova. "He's up there with Roger Clemens, as far as I'm concerned. Andre lied and got away with it. You can't correct that now. Do you take away a title he wouldn't have won if he had been suspended? He beat some people when he should have been suspended."

Current world number-one player Roger Federer said it "was a shock when I heard the news."

"I am disappointed and I hope there are no more such cases in the future. Our sport must stay clean," Federer said. Superstar Rafael Nadal added, "Cheaters must be punished and if Agassi was a cheater during his career, he should have been punished.

"To me it seems terrible," Nadal added. "Why is he saying this now that he has retired? It's a way of damaging the sport that makes no sense. I believe our sport is clean and I am the first one that wants that."

Agassi's former coach, Nick Bollettieri, said that Agassi's admission should be weighed against the rest of his life's work. "Let's look at what Andre has done; he funds a school for 400 kids from the inner-city. I know underneath he's a hell of guy," he said.