Lee passed away in 1973 at the age of 32 from cerebral edema, which could have been caused by a reaction to prescription painkillers.
But fans have long asked what would have happened if the martial arts legend, real name Lee Jun-fan, fought Ali in a blockbuster dream clash.
Enter the Dragon director Clouse, who worked closely with Lee for the 1973 cult classic, revealed that the Hong Kong-American former actor opened up about the outcome of the fight.
He wrote in the 1987 book The Making of Enter the Dragon: “Another time Yeung, aka [Bolo] went to see Bruce at Golden Harvest Studios. Bruce was screening a Cassius Clay [Muhammad Ali] documentary.
“Ali was world heavyweight champion at the time and Bruce saw him as the greatest fighter of them all.
“The documentary showed Ali in several of his fights. Bruce set up a wide full-length mirror to reflect Ali’s image from the screen. Bruce was looking into the mirror, moving along with Ali.
“Bruce’s right hand followed Ali’s right hand, Ali’s left foot followed Bruce’s left foot. Bruce was fighting in Ali’s shoes.
“‘Everybody says I must fight Ali someday.’ Bruce said, ‘I’m studying every move he makes. I’m getting to know how he thinks and moves.’
“Bruce knew he could never win a fight against Ali. ‘Look at my hand,’ he said. ‘That’s a little Chinese hand. He’d kill me.'”
Despite his tragic passing, fans have continued to debate how Lee would have held himself against other legends in crossover fights.
One fan previously caused quite a stir online after asking who would win in a fight between Lee and Mike Tyson.
Ali, who famously had a crossover fight with Antonio Inoki in 1976, suffered a long battle with Parkinson’s disease before he passed away in 2016 at the age of 74.