Leonard's career kicked off with a bang. He grabbed the light-welterweight gold at the 1976 Olympics in Montreal, Canada. Just months later, he jumped into the pro ranks.
By the end of 1979, Leonard had already clinched the WBC world welterweight title. He knocked out Wilfred Benitez in the final round of their Las Vegas showdown.
The summer of 1980 saw Leonard taste defeat at the hands of Roberto Duran. But he bounced back in their rematch, winning the famous 'No Mas' fight where Duran quit in the eighth round.
Leonard faced some of boxing's biggest names, including Roberto Duran and Marvin Hagler. But it's Hearns who stands out in his memory. During a 'Best I Faced' round, Leonard said:
"It was Tommy [Hearns]. I don't think anything matches our first fight."
That first fight, dubbed 'The Showdown', took place in September 1981. Leonard won by knockout in the penultimate round, unifying the WBC and WBA welterweight titles. The bout left a lasting impression on Leonard.
Four years later, they met again. This time, Leonard's WBC super middleweight title was on the line. The judges couldn't separate them, calling it a split-decision draw.
Fans hoped for a trilogy to settle the score, but it never materialized before both men hung up their gloves.
Leonard's choice of Hearns as his toughest opponent speaks volumes about 'The Hitman's' skills. Their battles in the ring have clearly stuck with Leonard, even after all these years.
Leonard's full 'Best I Faced' responses offer more insight into his storied career, but it's clear that Thomas Hearns left the biggest mark.