Leonard had won the WBC's world Welterweight title with a win over Wilfredo Benitez in 1979, lost it to Roberto Duran in 1980 and regained it from the same foe at the No Más Fight later that same year. In 1981, Leonard went on a short stint in the Jr. Middleweight division, where he conquered the WBA's world championship, beating the world champion , Ugandan Ayub Kalule, by knock out in round nine.
Hearns, by his part, had won the WBA's world Welterweight championship in 1980, knocking out Jose 'Pipino' Cuevas in round two, at Detroit. He kept busy defending his crown for the next year, fending off challenges from Randy Shields, Pablo Baez and Luis Primera.
Because Leonard was seen as a speedy boxer-puncher, and Hearns as an aggressive boxer with a hard punch, the public clamored for this fight to happen. After the contracts were signed by both boxers, many magazines wrote articles publicising the fight.
The fight began as expected, Leonard boxing from a distance, and Hearns head hunting. By the sixth round, Leonard was showing a nick over his eye, and Hearns had a sizeable lead on the cards. But Leonard hurt Hearns in that round, and suddenly, Hearns switched into a more conservative, strategic style of boxing, while Leonard turned into the head hunter. While Leonard closed the gap between the boxers on the scorecards, it was Hearns who still held a safe lead after round 12. Leonard's eye injury had grown into a very noticeable mark that almost closed his eye. It was during the moment between rounds 12 and 13 that Leonard's trainer , Angelo Dundee, said the now legendary words of "You're blowing it, son!! You're blowing it!!" to his protege.
Leonard was reinvigorated by those words, and he came out for round 13 roaring, dropping Hearns near the ropes with a combination and almost causing him to fall off the ring. Hearns rose, but he was dropped again near the end of the round, when he touched the canvas with his left hand after another combination.
Hearns seemed to be spent by the beginning of round 14, and Leonard pinned him against the ropes, where he unleashed a combination of punches until referee David Pearl stopped the contest, giving Leonard the unified world Welterweight championship by a technical knockout in round 14.
The fight had deep consequences for both fighters: Leonard's eye injury turned out to be a detached retina, for which he had to retire (for the first time) in 1982. He would come back and retire several times later, and he would win more world titles, but he was never able to sustain a return to boxing. He diversified, participating in commercials for Golden Skillet chicken, Ford trucks and Franklin sporting goods, among others.
Hearns resented all the attention given to Leonard after their first encounter. He went on to win more world championships, and he was involved in super-fights against Benitez, Duran and Marvin Hagler. But he still felt that resentment against Leonard, believing that it would have been him getting all the endorsements had Leonard not beaten him.
Their rematch finally came along eight years later, on June 12, 1989, again at the Caesar's Palace hotel. Despite the fact that both fighters were considered by many to be over the hill, as they say in boxing, the fight still raised much interest from boxing fans around the world.
Hearns dropped Leonard in round three, and again in round 11. He made good use of his jab during the fight, hurting Leonard repeteadly. But Leonard hurt Hearns in round 7, and a barrage of punches by Leonard late in round 12 had Hearns reeling against the ropes. Leonard's aggressiveness combined with Hearns' jab attack and his two knockdowns of Leonard, had the judges score the fight a draw.
Currently, Sugar Ray Leonard is a member of the International Boxing Hall of Fame. Hearns isn't, in part because he has kept on boxing until recently, but most critics agree that he will join Leonard there in due time. Hearns and Leonard have spoken after their two fights, and they seem to be on friendly terms.
Their rivalry is remembered by many critics and fans as one of the greatest in boxing history.