LAS VEGAS — Juan Manuel Marquez knocked Manny Pacquiao out cold with a vicious right hand at the end of the sixth round Saturday night, putting a ferocious end to the fourth fight between the two.

Pacquiao had been down in the third round but knocked Marquez down in the fifth and the two were exchanging heavy blows in the sixth before Marquez threw a right hand that put Pacquiao face down on the canvas at 2:59 of the round.