On December 11, 1981, a 39-year-old Muhammad Ali (56-4, 37 KOs) and a 27-year-old Jamaican boxer Trevor Berbick (19-2-1, 17 KOs) met in the ring.
Ali came in to the fight on a 1-fight losing streak with a 61% KO rate, and was fighting after a gap of 1 year, 2 months, and 9 days. Berbick was on a 1-fight win streak with a 77% KO rate, and fighting after a layoff of 4 months and 20 days.
Trevor Berbick defeated Muhammad Ali via unanimous decision in the 10-round fight. Berbick improves his record to 20-2-1, while Ali adds a loss to his record at 56-5.
On October 2, 1980, a 38-year-old Muhammad Ali (56-3, 37 KOs) got a shot at the heavyweight WBC title held by 30-year-old Larry Holmes (35-0, 26 KOs).
Ali came in to the fight on a 1-fight win streak with a 62% KO rate, and was fighting after a gap of 2 years and 17 days. Holmes was on a 35-fight win streak with a 74% KO rate, and fighting after a layoff of 2 months and 25 days.
The challenger refused to continue the fight in the 10th round, and Larry Holmes is crowned the new The Ring heavyweight world champion. Holmes improves his record to 36-0 (27 KOs), while Ali adds a loss to his record at 56-4.
On February 15, 1978, the 36-year-old undisputed heavyweight world champion, Muhammad Ali (55-2, 37 KOs), faced a 24-year-old Leon Spinks (6-0-1, 5 KOs) in an undisputed title defense fight.
Ali came in to the fight on a 14-fight win streak with a 64% KO rate, and was fighting after a gap of 4 months and 17 days. Spinks was on a 1-fight win streak with a 71% KO rate, and fighting after a layoff of 2 months and 28 days.
Leon Spinks defeated Muhammad Ali via split decision and wins the WBA, WBC, and The Ring heavyweight world champion — and becomes the undisputed heavyweight world champion — in his first world-title fight. Spinks improves his record to 7-0-1, while Ali adds a loss to his record at 55-3.
On March 31, 1973, a 31-year-old Muhammad Ali (41-1, 31 KOs) and a 29-year-old Ken Norton (29-1, 23 KOs) met in the ring in a heavyweight bout.
Ali came in to the fight on a 10-fight win streak with a 73% KO rate, and was fighting after a gap of 1 month and 17 days. Norton was on a 13-fight win streak with a 76% KO rate, and fighting after a layoff of 3 months and 18 days.
Ken Norton defeated Muhammad Ali via split decision in the 12-round heavyweight fight. Norton improves his record to 30-1, while Ali adds a loss to his record at 41-2.
On March 8, 1971, a 29-year-old Muhammad Ali (31-0, 25 KOs) got a shot at the undisputed heavyweight championship held by 27-year-old Joe Frazier (26-0, 23 KOs).
Ali came in to the fight on a 31-fight win streak with a 80% KO rate, and was fighting after a gap of 3 months and 1 day. Frazier was on a 26-fight win streak with a 88% KO rate, and fighting after a layoff of 3 months and 18 days.
Joe Frazier defeated Muhammad Ali via unanimous decision and successfully defended his WBA and WBC heavyweight titles. Frazier improves his record to 27-0, while Ali adds a loss to his record at 31-1.