Tyson quietly acknowledged to a judge that he had cocaine and was impaired when he was stopped for driving erratically in Scottsdale on Dec. 29.

He pleaded guilty to a single felony count of cocaine possession and a misdemeanor DUI count and faces up to four years and three months in prison when he is sentenced Nov. 19. A felony charge of possession of drug paraphernalia and a second misdemeanor DUI charge were dropped as part of a plea agreement.

Defense lawyer David Chesnoff said Tyson has been clean and sober for eight months.

"It's obvious this was a crime he was committing against himself," Chesnoff said.

Police stopped Tyson after the boxer had spent the evening at Scottsdale's Pussycat Lounge. An officer said he saw Tyson wiping a white substance off the dashboard of his black BMW, and that his speech was slurred. Authorities said they found bags of cocaine in Tyson's pocket and in his car.

In 1986, Tyson became the youngest heavyweight champion in history when, at 20, he knocked out Trevor Berbick. He lost his title four years later when he was knocked out by James "Buster" Douglas. By 1997, Tyson's career hit a low point when he bit Evander Holyfield's ear during a fight.