"Pretty Boy" Mayweather (39-0) sent "Hitman" Hatton (43-1) to the mat Saturday night with a hook to the left cheek.
Seconds later, Mayweather, 30, who has 25 KOs, put Hatton down for the count with a left hook to Hatton's head.
It was the biggest matchup of two undefeated welterweights since Oscar De La Hoya fought Felix Trinidad in 1999.
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