From The Washington Post:
Agassi was born in Las Vegas to a brutal Iranian immigrant, a former Olympic boxer, who forced his four children to play tennis. As a pre-schooler, Andre began hitting balls on the backyard court for hours every day. School, friends, social life and especially thinking were considered distractions by his father, who terrified the entire family. But while his sisters rebelled and his older brother, Philly, finally lacked the killer instinct, Andre became his father's obsession and whipping boy — one who was expected to whip other boys and unsuspecting men on court. His father pitted him at age 8 against suckers, including football great Jim Brown, who foolishly bet $500 that he could beat the kid. Before junior tournaments, Mr. Agassi fed his son caffeine-laced pills. Later, he tried to turn Andre on to speed.
At the age of 12, Andre traveled to Australia with a team of elite young players. For each tournament he won, he got a beer as a reward. Then in the seventh grade he was shipped off to the Bollettieri Academy in Florida, where his tennis flourished, but his life turned feral. Drinking hard liquor and smoking dope, he wore an earring, eyeliner and a Mohawk. Nobody objected as long as he won matches. The academy, in Agassi's words, was “Lord of the Flies with forehands.” Since the press and the tennis community still regard Nick Bollettieri as a seer and an innovator whose academy spawned dozens of similar training facilities, Agassi's critical opinion of him may shock the ill-informed. But in fact, Bollettieri is the paradigmatic tennis coach: that is, a man of no particular aptitude or experience and no training at all to deal with children.
More here.