"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.