Velasquez, who had originally lost his heavyweight title against Dos Santos at UFC on Fox 1, reclaimed the division's top honor at UFC 155. He battered "Cigano" for five rounds and established himself as the world's greatest heavyweight.
With one win apiece, these two heavyweight standouts will settle their score in the sport's biggest stage: the Octagon.
Click on for the Round 1 recap and analysis.
Junior dos Santos blasted Cain early with his meat-hammer fists, prompting the champ to immediately shoot in for a takedown.
That was fun.
"Cigano" avoided this early attempt, and the two broke, traded and clinched for a minute before Cain finally landed a takedown attempt.
Landing in half guard, Velasquez battered dos Santos with a vicious assault of elbows and punches from the top, but the challenger worked his way back to the feet, where they returned to the fence to close out the round with some dirty boxing.
Dos Santos ended the round with a spinning back kick that missed, reminding us of his vicious knockout over Mark Hunt just five months ago.
This is what we expected, right?
Velasquez's takedown attempts are absolutely relentless, and he is not giving dos Santos room to work. When separated, dos Santos has flashed his trademark power, but Cain is simply not giving him space.
While the champ did score a takedown or two, nothing of much significance resulted from them aside from the fact that he is establishing the tone and setting the pace for the rest of the fight.
Round 2 continued the trends we saw in Round 1.
This looks awfully similar to their UFC 155 encounter, which Velasquez dominated.
Now, the champ is taking over all aspects of the game, winning striking exchanges, grappling exchanges and clinch battles against the cage.
Dos Santos landed a beautiful short elbow that briefly buckled Velasquez as the round drew to a close, but we've seen nothing but the champion otherwise.
Cain took over the fight in all areas in this round.
With dos Santos worrying about the takedowns and beginning to slow a bit, he was free to open up with his hands and tee off on the Brazilian a bit.
This fight is favoring the champion more and more with every passing second.
Remember when Velasquez dropped and swarmed dos Santos at UFC 155 and we had no idea what was keeping Cigano on his feet?
Yeah, that happened again this round.
Velasquez obliterated dos Santos with a massive right hand, sending the challenger tumbling to the canvas. After a swarming guillotine attempt, dos Santos butt-planted again, and referee Herb Dean came within a nanosecond of stopping the fight.
Honestly, it looked like Dean tapped Cain on the back, signaling for him to stop, but he immediately retracted his decision, and the fight wore on.
Either way, this fight is getting out of hand just like their previous matchup at 155.
That hellacious right hand is all one needs to analyze, because it completely altered the landscape of this fight.
Before Velasquez dropped dos Santos, I still felt as though we might see a big punch or a powerful flurry from the challenger, but he now looks defeated, weak and gelatinous.
I would say that Cain will end this in Round 4, but we've seen dos Santos' heart, and I'm never counting him out after his valiant display at UFC 155.
A note from my editor that I simply must include:
"Dos Santos is the toughest SOB ever. This should have probably been stopped, but he's still in it."
He has a point. This is getting absurd.
The fact that dos Santos can stand is amazing; the fact that he's firing back and still actively trying to win this fight is borderline ridiculous.
Make no mistake: this fight is about Velasquez and his insane blend of speed, power and technique, but I can't help but be more drawn toward dos Santos' spirit.
The champion is still dominating in every way, but dos Santos is still there, and that, at this point, is incredible.
The doctors checked a cut on dos Santos' face in this round, but Cigano said he was fine.
Of course he did.
What can you say at this point?
Dos Santos is throwing a healthy dose of left elbows now, so I'm wondering if he injured his hand, but really, that doesn't matter.
Cain is going to work. It's a carbon copy of UFC 155.
Is this redundant? I'm sorry.
There's nothing to say. Cain is the best heavyweight in the world, and he's destroying dos Santos...again.
Junior dos Santos just knocked himself out.
He dropped for a guillotine, landed right on his head, and immediately turtled up in a daze.
I cannot believe the fight ended that way, but there you have it.
The TKO for Velasquez is quite deserved, but it's more than just a little disappointing to see it end like that.
Crazy. This is why we watch, folks.
Only Gray Maynard will agree that dos Santos' fall in Round 5 was graceful.
A self-KO was unexpected from the challenger, but Velasquez certainly earned a stoppage victory with his relentless pace and high volume of pinpoint punches and elbows. He was downright nasty, and it's hard to imagine the guy who will properly challenge him inside the Octagon in the near future.
Velasquez is the greatest heavyweight in the world, and I'll take it one further and say he is the greatest heavyweight in UFC history.
He still has a lot of work to do to usurp Mr. Fedor Emelianenko as the greatest heavyweight of all time, but if I had to pick somebody to do, I'm taking the world-class wrestler with powerful fists, excellent technique and the cardio of a lightweight.
He is an animal, and we are lucky to watch him go to work inside his cage.