The actor performed his iconic impression of the heavyweight champ as he shared touching memories at Ali's funeral.
The world heard Muhammad Ali speak one last time -- through "little brother" Billy Crystal's infamous impression of the boxer.
Following the Islamic prayer service held for the three-time heavyweight champ on Thursday, his family, friends and thousands of fans turned out at the KFC Yum! Center in Louisville, Kentucky, on Friday to lay the legend to rest. Among the handful of eulogizers was Crystal, Ali's friend of 42 years.
"Today, this outpouring of love and respect proves that 35 years after he stopped fighting, he is still the champion of the world," Crystal began. "Last week, when we heard the news, time stopped. There was no war. There was no terrorism...The world stopped, took a breath, and sighed."
"Every moment that I've known him is cherished," the actor told the audience.
Ali and Crystal first me when the then-relatively unknown comedian performed on television for the first time during a special honoring the boxer in 1974, debuting his now-infamous Ali impression and creating a lifelong bond with the athlete.
"That's when I saw him for the first time in person. It's very hard to describe how much he meant to me. You had to live in his time," Crystal said. "To live in his time, watching his fights, experiencing the genius of his talent was absolutely extraordinary."
"He was funny, he was beautiful, he was the most perfect athlete you ever saw and those were his own words," he added. "But he was so much more than a fighter."
Crystal went on to recall his favorite memory with Ali -- of the "many funny, unusual moments with him" -- performing during the boxer's retirement celebration in 1979. It's a comedy routine titled "15 Rounds" and Crystal shared it on Twitter last week, tweeting, "For the greatest man I have ever known."
WATCH: Muhammad Ali Remembered by Family and Thousands of Fans During Islamic Prayer Service
"There were 20,000 people but I was doing it only for him," Crystal recalled. "It's one of my favorite performances I've ever done in my entire life. I sort of got lost in him...[Afterward] he whispered in my ear, with a big bear hug, 'Little brother, you made my life better than it was.' But didn't he make all of our lives better than they were?"
"He taught us life is best when we build bridges between people, not walls," he added of Ali's legacy. "My friends, only once in a thousand years or so, do we get to hear a Mozart or see a Picasso or read a Shakespeare. Ali was one of them."
"He is gone, but he will never die," Crystal concluded. "He was my big brother."
ET exclusively sat down with Ali's daughter, Laila, who reflected on the special bond she had with her father and gushed over Will Smith's "phenomenal" portrayal of him. Hear what she had to say in the video below.