In an interview with The Ring Magazine, Ali looked back on his toughest fights. You'd think he'd pick the famous 'Rumble in the Jungle' against George Foreman in Kinshasa, Zaire. Ali said:
"There was probably no bigger challenge in my career than the one George Foreman posed in Kinshasa, Zaire. Strangely, although regaining my crown will remain one of my greatest thrills, it wasn't one of my toughest fights."
Instead, Ali pointed to his first world title bout against Sonny Liston in 1964. Back then, he was still known as Cassius Clay and came into the fight as a 7-1 underdog. Most sportswriters thought it'd be over quick.
Ali recalled:
"Sonny came out at the bell looking to take me apart. I moved and stuck, knowing that I was going gaining control in the second round. But the "Bear" was always dangerous. Stalking, glaring, mean."
Things got really tough for Ali in the fourth round:
"About the fourth round my eyes stated burning. Finally, when I came back to my corner, I couldn't see at all. I figured Liston had something on his gloves and asked Angele [Dundee] to cut my gloves off. He didn't but gave my eyes a good wash, checked Liston's corner, talked to the referee and tried to stall for more time."
Some folks thought Liston and his cutman might have blinded Clay on purpose. Others said it was just sweat from the clinches.
Ali kept fighting:
"Like a wounded animal, with eyes swollen and cut, Sonny came out with a surge in the sixth round and connected with a good right hand but he couldn't keep it going and I ended the round feeling like I was the new champ. But I was still very relieved to see big Sonny remain on his stool when the bell rang for the seventh. I still respect him as one of the truly great heavyweights of all time."
Before the fight, Ali had made one of his famous predictions: "Then Clay lands with a right, what a beautiful swing, And the punch raised the bear clear out of the ring." It wasn't quite as spot-on as some of his later predictions, but he got the win when Liston didn't come out for the seventh round.
They fought again, and Ali stopped Liston in the first round. Some people said Liston might have thrown the fight, but that's a story for another day.