Andre Agassi's upcoming autobiography contains an admission that he used crystal meth in 1997 and lied to tennis authorities when he failed a drug test - a result that was thrown out after he said he "unwittingly" took the substance.

According to an excerpt from the autobiography posted on the Times of London's website Tuesday, the eight-time Grand Slam champion writes that he sent a letter to the ATP tour to explain the positive test, saying he accidentally drank from a soda spiked with meth by his assistant 'Slim'.

"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. The ATP reviewed the case - and threw it out."

Anti-doping rules

Under today's anti-doping rules, a player could face a ban of up to two years for use of the drug.

World Anti-Doping Agency (WADA) president John Fahey said the body can't take any action against Agassi because of its eight-year statute of limitations and that it's "unlikely" the ATP will either.

"WADA would, however, expect the ATP, which administered its own anti-doping programme at that time, to shed light on this allegation," Fahey said in a statement.

International Tennis Federation (ITF) president Francesco Ricci Bitti said he was "surprised and disappointed" by Agassi's disclosures.

Ricci Bitti said the incident occurred before WADA was founded in 1999 and when drug-testing was handled by individual governing bodies. The ITF assumed responsibility for the ATP's anti-doping programme in 2006 and for the WTA Tour in 2007.

"We would hope that Andre Agassi might now see his way to be a role model and alert youth and tennis players to the dangers of drug use and doping," Fahey said.

Introduction to drugs

Agassi retired in 2006. Excerpts from his autobiography, which comes out November 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 website 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 the Times of London's website, 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."

Among the most successful - and, without a doubt, one of the most popular - tennis players in history, Agassi drew attention not just for his play, but also for his outfits, his hairstyles and his relationships with women, including a failed marriage to actress Brooke Shields.

In a posting on People's website, 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 Times of London's excerpt, Agassi was walking through New York's LaGuardia airport when he got the call that he had failed a drug test.

Penalty

"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."