Canelo Alvarez stopped Billy Joe Saunders as the British corner threw in the towel with an apparent eye injury on Saturday night in Dallas.
The fight was close for eight rounds, but Billy Joe was unable to continue and the fight was called off before the start of the ninth.
The fight began with an intriguing opening round as Saunders used a number of punches while Canelo successfully targeted the body.
The Mexican landed his first big punches in the second as he caught up to his opponent with a few straight straights, but the Briton looked unfazed and responded with more consistent punches.
Canelo continued to crank up the tempo in the third round and confused Saunders for feints before hammering home body shots.
Billy Joe shook his head in response and walked away from Alvarez.
The fourth was a quieter session with Canelo continuing his efficient bodywork and landing a noticeable uppercut nearby that nearly knocked out Saunders mouthpiece.
The fifth round saw better times for the Briton as his production increased.
He continued that momentum as they approached halfway and started to land with more consistency while frustrating and taunting Canelo.
The Mexican tried to regain control in the seventh, targeting the body again with good success.
Saunders responded well, but was injured for the first time in the eighth round as he retreated after being caught with a big meter on the right.
It would soon become obvious how much damage that punch had done.
Canelo chased his opponent around the ring and landed some big shots. The Briton survived the round, but did not emerge for the next.
It was clear that there was a serious problem with Saunders eye in the corner and his team stopped the fight, crowning Canelo as the unified WBA, WBC and WBO super middleweight world champion.
He now wants the IBF belt from Caleb Plant.
Canelo said after the fight: “I think I broke my cheek and I knew he wasn’t coming back…
“Caleb Plant, for the belt. I’m coming man, I’m coming my friend. Hope we can give the fans this fight. “
Eddie Hearn explained of the shutdown: “He couldn’t see. I spoke to Mark Tibbs, he said he couldn’t see and wouldn’t let him out. He broke his eye socket.