When Joe ‘The Brown Bomber’ won the world heavyweight title by beating champion James Braddock in June 1937, he said, “Until I beat Max Schmeling, I’m not the champion!” He talked about his KO loss in 1936. He avenged it in 1939 at Madison Square Garden, knocking out Schmeling in the first round.
When “Sugar” Ray Leonard, 27-0, lost to Roberto “Hands of Stone” Duran, 71-1, in June 1980 fighting Durans fight, he had a rematch. He boxed Duran so badly that Duran left on the stool in November.
In April 1987, Leonard defeated Marvin Hagler for his middleweight title. Hagler retired and moved to Italy, not wanting a rematch.
In April 2002, Lightweight champion Floyd “Money” Mayweather took a split decision over Jose Luis Castillo. Eight months later, he gave a rematch, defeated easily.
In June 2012, Manny ‘Pac Man’ Pacquiao was robbed by Tim Bradley, Jr., but in April 2014, he defeated Bradley in a rematch.
In November 2016, Andre “SOG” Ward received a split decision over Sergey Kovalev in a fight for the lightweight title and gave him an immediate rematch, stopping Kovalev, then retired from boxing.
Heavyweight champion Rock Marciano took a close, if uncontested, decision over Roland LaStarza in March 1950 before winning the title. After signing “Jersey” Joe Walcott for the title and again in his next fight, he signed LaStarza.
In November 1986, Super Featherweight champion Alfredo Escalera won a split decision over Philadelphia’s Tyrone Everett in Philadelphia. He never got a rematch, and the Pennsylvania judge who voted for Escalara never worked another show.
Historian Jim Jacobs told me that the worst decision he ever saw was in June 1963, when lightweight champion Harold Johnson was robbed by Willie Pastrano by split decision and never got a revenge
Heavyweight champion Muhammad Ali lost to Ken Norton and Smokin’ Joe Frazier in their first fights, but defeated them twice in rematches.
In June 1983, heavyweight champion Larry ‘The Easton Assassin’ Holmes, 42-0, received a decision in a defense against the “Terrible” Tim Witherspoon, 15-0, and did not he ever gave a rematch.
What fight did you want to see in a rematch that never happened?