Saul 'Canelo' Alvarez admitted he thought Billy Joe Saunders had suffered a broken cheekbone after he caught the Englishman with a flurry of punches on his way to a unification victory in Texas.
A vicious uppercut during the eighth round saw the bout halted prematurely after Saunders' trainer Mark Tibbs called an end to proceedings before the ninth round.
While the judges had Alvarez ahead on all three cards, the Briton had briefly stunned the Mexican in the fifth with a strong left hook but it was not enough.
The WBA, WBC and WBO-title holder told reporters at a post-fight press conference: "Not much to say (to Billy Joe), he is a great fighter, like I said. This fight couldn't happen without him. I'm glad he took the fight and we will continue to make history.
"It's hard because I saw when he broke his cheekbone and I went back to the corner and told my trainer Eddie 'I didn't think he could continue' because when you break a cheekbone, you risk your life and you can't continue that way."
Saunders was unbeaten in 30 fights before the super-middleweight clash in Arlington and the southpaw started well in front of more than 73,000 people, which set a new record attendance for an indoor boxing event in the United States.
The 31-year-old's confidence started to grow in the middle rounds and he even taunted the Mexican by poking out his tongue during the sixth, but trouble was on the horizon.
With Tyson Fury watching from the crowd, a devastating blow in the eighth caught Saunders near his right eye, which affected his vision and resulted in trainer Tibbs ending the contest with three rounds to go.
"I knew what I was doing and I knew what I did with that punch, I knew he wouldn't come back after I broke his cheekbone. I love boxing and this is what I love to do," Alvarez, who has 56 wins, two draws and one loss, added.
"I'm happy and grateful with the fans, happy to come back to normal and break records, even in a pandemic they came out and supported me. I'm really grateful.
"Eddie told me before when I dominate him, to turn to the people and talk to them and connect with them. That's what I did."
Alvarez's press conference was briefly interrupted by Demetrius 'Boo Boo' Andrade, who congratulated the four-division world champion before a war of words developed and the American was escorted out after receiving a flurry of expletives from the Saturday night victor.
While Andrade has desires on facing the Guadalajara-born fighter next, IBF champion Caleb Plant is in the sights of Saunders' conqueror, who wants to claim all four major world titles at 168lbs.
Alvarez has now defeated seven English fighters, including Callum Smith in December, and was promoted by Eddie Hearn for this contest, who lauded the 30-year-old after the AT&T Stadium bout.
The Matchroom chief said: "There is no excuse why the Caleb Plant fight shouldn't be made. In terms of stars, I've not seen anything like that.
"Of course Anthony Joshua in the UK, but in America and around the world, the numbers and interest, the digital numbers all week and the numbers globally on DAZN, Canelo is a superstar."