Andre Agassi's upcoming autobiography contains an admission that he used crystal meth in 1997, the year he dropped to No. 141 in the rankings.
In an excerpt posted on People magazine's Web site Tuesday, Agassi writes: "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."
Excerpts from the book are being printed this week by People and Sports Illustrated. A writer from SI first revealed the crystal meth reference on a Twitter posting Tuesday.
Knopf spokesman Paul Bogaards told The Associated Press that the tweet was accurate.
Agassi won eight Grand Slam singles titles before retiring in 2006.
His book's publishing date is Nov. 9.