"He cuts it, snorts it. He cuts it again. I snort some.
"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."
Crystal meth is classified in the UK as a class A drug - the category for those considered to be the most harmful and which attract the most serious punishments and fines.
It looks like small ice crystals and is a very powerful and addictive form of the stimulant speed, which can be eaten, inhaled through the nose or injected.
Agassi, who is widely considered to be among the greatest tennis players of all time, recounts in the book, which is called 'Open', about his introduction to the drug.
He was enduring the worst year of his professional career in 1997 as he struggled with a wrist injury, and his world ranking slumped to a low of 141 that November.
Agassi, who is married to former women's world number one Steffi Graf, explained how he had received a call from an ATP at that time to inform him he had failed a drugs test.
I say [in a letter] Slim, whom I've since fired, is a known drug user, and that he often spikes his sodas with meth - which is true
Former tennis star Andre Agassi
The Las Vegas-born star wrote a letter to the ATP to argue the use was accidental, blaming his former assistant Slim.
"My name, my career, everything is now on the line. Whatever I've achieved, whatever I've worked for, might soon mean nothing," Agassi writes.
"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.
"I say Slim, whom I've since fired, is a known drug user, and that he often spikes his sodas with meth - which is true. Then I come to the central lie of the letter.
"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, who is often cited as one of the most charismatic players ever, writes that the ATP reviewed his case and, while he faced a minimum three-month ban, decided to believe his account and withdraw the charges.
His subsequent rise back through the rankings over the following two years, on the back of a gruelling fitness programme and the ignominy of playing on the lesser Challenger circuit, has gone down in tennis history.
Archive video: Agassi and wife Steffi Graf on Inside Sport, May 2009
In 1999 Agassi became only the fifth man to win all four Grand Slam titles with victory at the French Open. Three months later he added a second US Open crown and he ended the year back at number one in the world.
Former Wimbledon champion Michael Stich told BBC Radio 5 live the revelations raised questions about the ATP's handling of the matter.
He suggested Agassi was not suspended "because he was so important to the game".
The German said: "The fact that he was using it [crystal meth], escaped drugs tests and said he used it accidentally raises a lot of questions towards the ATP.
"Why was Andre Agassi not suspended if he tested positive and why was it never brought to the attention of the media and the players? Nobody ever heard about it."
An ATP spokesman said it commented on the results of drugs tests only when a violation had occurred, and so could not speak about the Agassi situation because it withdrew the case against him.
"Under the tennis anti-doping programme it is, and has always been, an independent panel that makes a decision on whether a doping violation has been found," he stated.
"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."
Expressing his disappointment about the revelation, Wada president John Fahey said Agassi was seen as a role model who should alert youths to the dangers of doping.
This raises a lot of questions towards the ATP. Why was Agassi not suspended if he tested positive?
Former Wimbledon champion Michael Stich
Fahey said he expected the ATP to "shed light on this allegation."
The ITF said tennis authorities were determined to keep drugs out of the sport.
"This should not be overshadowed by an incident that took place over 12 years ago," said president Francesco Ricci Bitti.
"The statements by Mr Agassi do, however, provide confirmation that a tough anti-doping programme is needed."
BBC Radio 5 live's tennis correspondent Jonathan Overend feels Agassi's legacy could be ruined by the revelations and will also damage tennis's reputation.
"This is sure to severely tarnish the reputation of one of the great champions," said Overend.
"I think it will have underlying implications for the sport in terms of the suspicion about some of the athletes and whether or not they are on drugs.
"The fact that Agassi lied and the authorities believed him has enormous repercussions. How many other cases may there have been like this?"
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