"Then I come to the central lie of the letter," Agassi writes. "I say that recently I drank accidentally from one of Slim's spiked sodas, unwittingly ingesting his drugs. I ask for understanding and leniency and hastily sign it: Sincerely.

"I feel ashamed, of course. I promise myself that this lie is the end of it."

Agassi said the ATP reviewed the case, accepted his explanation and threw it out. The tour responded with a statement, noting an independent panel makes the final decision on a doping violation.

"The ATP has always followed this rule, and no executive at the ATP has therefore had the authority or ability to decide the outcome of an anti-doping matter," the statement said.

The International Tennis Federation said it was "surprised and disappointed" by Agassi's revelations.

"Such comments in no way reflect the fact that the tennis anti-doping program is currently regarded as one of the most rigorous and comprehensive anti-doping programs in sport," the ITF said in a statement.

In the past three years, the organization has begun overseeing anti-doping efforts on behalf of the ATP and WTA tours.

"The events in question occurred before the World Anti-Doping Agency was founded in 1999 and during the formative years of anti-doping in tennis, when the program was managed by individual governing bodies," the ITF said.

The president of WADA, Jim Fahey, said he was disappointed by Agassi's revelations and expects the ATP to "shed light on this allegation."

Agassi, who married tennis star Steffi Graf and has two children, retired in 2006. Excerpts from his autobiography, which comes out Nov. 9, are being published this week in the London newspaper, as well as Sports Illustrated and People magazines.

In a story posted on People magazine's Web site Tuesday, Agassi says: "I can't speak to addiction, but a lot of people would say that if you're using anything as an escape, you have a problem."

According to the Times of London, Agassi writes in his book that "Slim" was the person who introduced him to crystal meth, dumping a small pile of powder on the coffee table.

"I snort some. I ease back on the couch and consider the Rubicon I've just crossed," Agassi writes.

"There is a moment of regret, followed by vast sadness. 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."

"I'm seized by a desperate desire to clean. I go tearing around my house, cleaning it from top to bottom. I dust the furniture. I scour the tub. I make the beds."

U.S. Fed Cup captain Mary Joe Fernandez, a contemporary of Agassi's, described the revelations as disappointing and "a bit of a shock."

"It takes a lot of guts and courage to come out and say something that nobody would have really known about," Fernandez said. "I've always admired Andre. He was a huge part of inspiring my generation, and he did a lot of great things and continues to do a lot of great things. He's opening up now, and that's his choice. Maybe people can learn from it and not make the same mistakes."

Among the most successful and popular tennis players in history, Agassi drew attention not just for his play, but also for his outfits, hairstyles and relationships with women, including a failed marriage to actress Brooke Shields.

Agassi's first major championship came at Wimbledon in 1992, and he won a gold medal at the 1996 Atlanta Olympics. But by late 1997, he dropped to No. 141 in the rankings, and he was playing in tennis' equivalent of the minor leagues.

He resuscitated his career in 1998, making the biggest one-year jump into the top 10 in the history of the ATP rankings. The next season, he won the French Open to complete a career Grand Slam, then added a second career U.S. Open title en route to finishing 1999 at No. 1.

After an exhibition match Sunday in China against longtime rival Pete Sampras, Agassi was asked if his autobiography contained any major revelations.

"I think I had to learn a lot about myself through the process," Agassi said. "There was a lot that even surprised me. So to think that one won't be surprised by it, it would be an understatement.

"Whatever revelations exist, you'll get to see in full glory," he added. "But the truth is, my hope is that somebody doesn't just learn more about me, what it is I've been through, but somehow through those lessons, they can learn a lot about themselves. And I think it's fair to say that they will."

In a posting on People's Web site, Agassi says he "was worried for a moment, but not for long," about how fans would react if they found out he used drugs.

"I wore my heart on my sleeve and my emotions were always written on my face. I was actually excited about telling the world the whole story," Agassi says. According to the publisher, he worked closely on the book with Pulitzer Prize-winning journalist J.R. Moehringer, author of "The Tender Bar."

A writer from SI first revealed the crystal meth reference on a Twitter posting Tuesday.

According to the Times of London excerpt, Agassi was walking through New York's LaGuardia airport when he got the call that he had failed a drug test.

"There is doom in his voice, as if he's going to tell me I'm dying," Agassi writes. "And that's exactly what he tells me."

"He reminds me that tennis has three classes of drug violation," Agassi writes. "Performance-enhancing drugs ... would constitute a Class 1, he says, which would carry a suspension of two years. However, he adds, crystal meth would seem to be a clear case of Class 2. Recreational drugs." That would mean a three-month suspension.

"My name, my career, everything is now on the line. Whatever I've achieved, whatever I've worked for, might soon mean nothing. Days later I sit in a hard-backed chair, a legal pad in my lap, and write a letter to the ATP. It's filled with lies interwoven with bits of truth."

Fernandez said the episode didn't shake her faith in tennis' anti-doping program.

"WADA's drug testing is so severe I can't imagine anybody getting away with anything now," she said. "Players are getting tested in and out of competition at least 25 to 30 times a year."

In 2007, Martina Hingis tested positive for cocaine after a third-round exit at Wimbledon. She denied using the drug but was banned for two years. In July, Frenchman Richard Gasquet was cleared to resume playing after a 2½-month ban upon persuading the ITF's tribunal panel that he inadvertently took cocaine by kissing a woman in a nightclub.