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Juan Manuel Marquez, from Mexico, right, lands a right to the head of Manny Pacquiao, from the Philippines, during their WBO world welterweight fight Saturday, Dec. 8, 2012, in Las Vegas. Marquez won by a knockout. (AP Photo/Julie Jacobson)

Juan Manuel Marquez, from Mexico, right, lands a right to the head of Manny Pacquiao, from the Philippines, during their WBO world welterweight fight Saturday, Dec. 8, 2012, in Las Vegas. Marquez won by a knockout. (AP Photo/Julie Jacobson)

Manny Pacquiao - Juan Manuel Marquez IV

December 10, 2012

Manny Pacquiao was dropped by a vicious right hand by longtime rival Juan Manuel Marquez in the sixth round as the two fought for the

fourth time at the MGM Grand Garden Arena in Las Vegas, Nev. on Saturday, Dec. 8, 2012.