Saul 'Canelo' Alvarez (56-1-2, 38KOs) produced a devastating uppercut to leave a distraught Billy Joe Saunders (30-1, 14KOs) unable to rise from his stool after eight rounds of their world title unification bout in front of a record attenadance of over 73,000 fans.
Just as Hatfield's Saunders looked to be gaining a footing, the Mexican found a shot which caused an instant swelling over the British fighter's right eye.
Saunders' trainer Mark Tibbs rightfully called the bout off, with his fighter unable to see.
"I think I broke his cheek," said Alvarez. "The truth is I knew it."
Pound-for-pound No.1 Alvarez, 30, added: "I guessed in the corner and told my trainer Eddie Reynoso 'I broke his cheek'."
Within seconds of landing the pin-point blow - made more forceful by the fact Saunders was crouching into the shot - Alvarez raised his hands in front of his rival, ruthlessly letting the 73,126 fans in attendance know that he had broken the resistance of a man now at his mercy.
The scorecards after eight rounds read: 78-74, 78-74 and 77-75 - all for Canelo.
Two-weight world champion Saunders, 31, was taken to hospital with a suspected broken eye socket, an injury which has proven difficult to overcome for the likes of British fighter Kell Brook in recent years.
As an emotional Canelo was left in the ring thanking what was a record indoor crowd for a boxing event in the US, footage on the big screen inside Arlington's AT&T Stadium showed a heartbroken Saunders visibly in pain on his walk back to his changing room.
Four-weight ruler Canelo now has the WBC; WBA Super; WBO; and Ring Magazine titles. His next fight will be against IBF super-middleweight titlist Caleb Plant in his bid to become 'Undisputed' champion.
Cuban world heavyweight ranked Frank Sánchez (18-0, 13 KOs) defeated Nagy Aguilera (21-11, 14 KOs) by technical decision in the sixth round to retain his WBC Continental Americas title.
For the sixth round of a fight dominated by the Cuban, based on pressure, it was determined that Aguilera could not continue fighting, due to an accidental foul that Sánchez landed a right hand to the back of the head. All three judges scored the six-round bout with identical scorecards of 60-54.