Marquez knew Pacquiao’s weaknesses
In any sport, it’s hard to defeat a formidable opponent four times in a row. In boxing, it’s almost impossible. After the first three fights, Marquez was able to study Pacquiao and learned his weaknesses. Pacquiao often drops his left hand when throwing his right. Marquez took advantage of that weakness and used a counter punch to knock Pacquiao down early in the fight. The second time, Pacquiao never recovered from the counterpunch.
