Juan Manuel Marquez has nothing left to prove.
That became apparent right around the same time Manny Pacquiao was hitting the canvas for the second time on Saturday night.
With that sudden thud, with that one "perfect punch," as Marquez described it, the man known as "Dinamita" accomplished what he had been trying to do for the last decade:
Beat Manny Pacquiao.
It's not like Marquez had never given Pac-Man a good contest. During the first fight, he knocked down the pride of the Philippines twice in the first round and worked him to a draw. In the next two, he lost via decision, but they were both fights that could have easily gone both ways.
Yet no matter how close the final decisions were, the record between the two rivals remained the same: Manny Pacquiao was undefeated against Juan Manuel Marquez.
And unfortunately for Marquez, that, in the end, was all most people saw.
Dinamita's career had been chalk-full of success. He had beaten guys like Marco Antonio Barrera, Joel Casamayor and Juan Diaz, among others. He had won 54 fights (40 by knockout) and lost just six.
According to some, he was already a Hall of Famer.
But Marquez' brilliant career was never truly going to be complete until Manny Pacquiao, the man he couldn't beat, hit that canvas.
Of course, with a career-defining win like that comes more opportunities. Marquez could potentially get a rematch with Floyd Mayweather, who won fairly easily back in 2009. He could fight Timothy Bradley or a number of other intriguing names in the weight class. He could fight Manny Pacquiao for a fifth time.
Any of those would undoubtedly bring Marquez a large payday now that he's the guy who dropped "the best pound-for-pound boxer in the world" like a sack of potatoes.
And, in my opinion, it wouldn't be surprising if the veteran did schedule another fight.
But he doesn't have to. His career is now complete. He is now a Hall of Famer. He can now retire on top.