Via Ken Hissner: There were many lower weight champions who tried to win the heavyweight belt and failed until September 1985 when light heavyweight champion Michael “Jinx” Spinks defeated heavyweight champion Larry “Easton Assassin” Holmes .
In April 2003, light heavyweight champion Roy Jones, Jr defeated heavyweight champion John Ruiz to win the WBA title. Referee Jay Nady was very supportive, who did not allow Ruiz to continue playing as usual. Then in September 2021, cruiser champion Oleksandr Usyk defeated heavyweight champion Anthony “AJ” Joshua.
Before Spinks, Jones, Jr. and Usyk won the heavyweight belt in May 1909, former Philadelphia light heavyweight champion Jack O’Brien at 162 ½ drew with heavyweight champion Jack “Galveston Giant” Johnson.
In October 1909, middleweight champion Stanley “The Michigan Assassin” Ketchel knocked out heavyweight champion Johnson before being eliminated in the 12th round.
Great underweight champions like light heavyweight champion Georges “The Orchid Man” Carpentier in July 1919 lost to heavyweight champion Jess Willard and again in 1921 to heavyweight champion Jack Dempsey.
In September 1929, light heavyweight champion Tommy “Phantom of Philly” Loughran lost to heavyweight champion Jack “Boston Gob” Sharkey in three rounds. In March 1934, despite being a former light heavyweight champion, he lost to Primo “The Ambling Alp” heavyweight champion Carnera weighing 186 and Carnera 270.
In June 1941, light heavyweight champion Billy “Pittsburgh Kid” Conn, after 12 rounds, led heavyweight champion Joe “The Brown Bomber” Louis by 7-5, 6-6. and 7-4 when he was eliminated by Louis in the thirteenth round.
In June 1946, as both Louis and Conn were in the army, they had a long-delayed rematch, with Louis eliminating Conn in eight innings.
In September 1955, light heavyweight champion Archie “The Old Mongoose” Moore defeated heavyweight champion Rocky Marciano in the second round, only to be eliminated in the ninth round. The following year Moore again attempted to win the vacant heavyweight belt before being defeated by heavyweight champion Floyd Patterson in five rounds.
In November 1970, light heavyweight champion Bob Foster was defeated by heavyweight champion ‘Smokin’ Joe Frazier in two rounds. In November 1972, Foster was defeated by heavyweight champion Muhammad Ali in eight rounds.
