Amid all his bluster, his iconic status and his politics, it's sometimes easy to forget that Muhammad Ali was a truly astounding boxer.
Here's a reminder, from his 1966 fight with Brian London, during which he fires off a dozen punches in three seconds.
It's absolutely terrifying to think about.
Another famous instance of his speed was the notorious 'Phantom Punch' during his second fight with Sonny Liston.
Many in the crowd did not see the lightning jab, midway through the first round, and it was so contentious that some said the fight was a fix.
Tex Maule of Sports Illustrated later wrote:
The blow had so much force it lifted Liston's left foot, upon which most of his weight was resting, well off the canvas.
Jimmy Jacobs, who co-managed Mike Tyson, later used a synchroniser to measure a young Muhammad Ali's punch speed against Sugar Ray Robinson - a middleweight often considered the best pound for pound fighter ever.
While Robinson's punch took 8.5 frames of film, Ali's took only 6.5 - Ali was nearly 25 per cent faster despite being roughly 50 pounds heavier.