The 39 year-old was attempting to claim victory over the eight-weight champion for this first time after believing he had done enough in their first three meetings, of which none were given his way of the scorecards.
The fight was a boxing spectacle from start to finish as both boxers immediately sought a knockout, as promised, and Marquez drew first blood after dropping Pacquiao heavily in the third after a slow start.
‘Dinamita’ kept up his pressure in the fourth as Pacquiao appeared to still be shaken by the punch, although had fully recovered by the fifth to himself put Marquez on the canvas with flash knockdown.
As Pacquiao, 33, looked to end the entertaining bout there and then, both warriors stood and traded for the remainder of the round and the crowd where on their feet after possibly witnessing the round of the year.
In the sixth, both fighters picked up where they left off until Marquez pulled out a huge right that caught Pacquiao awkwardly, but the power in the shot relieved the ‘Pacman’ of all his senses and he hit the ground without moving.
Pacquiao then worryingly stayed down for a short period as the anxious crowd looked on, but eventually came to his senses a few moments later to realise that Marquez has claimed the victory in amazing fashion.
Prior to the contest, the two champions had stated that there would never be a fifth outing between them, although on this evidence there is definitely room for one more bout between the two after a Fight of the Year candidate at the MGM.