As the last round entered its final minute, Norton delivered an uppercut that knocked out Holmes' mouthpiece. Momentarily stunned, Holmes responded with a sustained flurry of punches that badly staggered Norton with the seconds ticking down.

"No one thought I could beat Norton," Holmes said. "No one thought I could be heavyweight champion of the world. I worked him. That was 15 rounds of fighting, something they don't do today."

Holmes said the most emotional night of his reign came in October 1980 when he faced Ali, his friend and mentor. The aging Ali was returning to the ring trying to win the heavyweight title for an unprecedented fourth time. Holmes dominated the fight, finally causing Angelo Dundee to throw in the towel after the 10th round - the TKO was the only nondecision loss of Ali's career.

"Emotionally, it was a tough fight," Holmes said. "I love the guy. He was 38 years old, and they were calling him an old man and washed up. So if I beat him, so what? I was in a no-win situation."

Holmes string of successful title defenses came ended in 1985 when he was upset by Michael Spinks in a 15-round decision. In 1986, Holmes lost a rematch with Spinks by a disputed split decision and retired temporarily.

In 1988, the then 38-year-old Holmes was lured out of retirement by a $3 million purse to challenge Mike Tyson, the undisputed champion. Tyson knocked out Holmes in the fourth round, the first and only time Holmes would be knocked out in his career. Holmes again retired.

He returned to the ring again in 1990. In 1992, he upset undefeated 1988 Olympic heavyweight champ Ray Mercer, but lost a 12-round decision to Evander Holyfield in a title fight. Holmes got a last title shot in 1995 at 45, losing the WBC title by decision to Oliver McCall.

Since retiring, Holmes has become a successful businessman. He owns a nightclub and restaurant to go with real estate ventures and his boxing training facility. He does speaking tours, was featured in a documentary and starred in a TV reality show.