The hostility carried over into fight night, as neither man extended a hand after receiving final instructions from the referee -- which is a normal show of respect toward the opponent.
There was no respect on this night.
But when the fisticuffs started, Belfort was the guy who unleashed his fury. A spinning kick caught Rockhold on the chin and sent him to the canvas.
Belfort (23-10) immediately jumped on his fallen opponent and delivered punches to Rockhold's chin, forcing referee Leon Roberts quickly to get between the fighters to end the devastating assault.
"I'm stronger than ever," said Belfort, whose knockout came at 2:32 of the first round. "I'm stronger than I was before.
"I have a great team in [the Boca Raton, Fla.-based] Blackzilians."
It was the manner in which Belfort was allowed to build up his strength that got under the skin of Rockhold. The former UFC light heavyweight champion received approval for testosterone replacement therapy before the fight.
The issue was a major source of hostility between the fighters. But while they showed no respect toward one another before the fight, Belfort spoke briefly to Rockhold afterward. It was the only sign of respect the two shared throughout the entire fight ordeal.
The strategy for Rockhold was clear entering this fight: Be patient early and don't allow Belfort to lure him into a slugfest. If Rockhold could survive Belfort's early attack, he'd be in position to step up his attack in the latter rounds, he thought.
But Rockhold never got a chance to apply his fight plan.
"I take my hat off," Rockhold said after falling to 10-2 and watching his win streak stopped at nine.
"He landed a spinning heel kick to my head. I didn't see that one coming. What can I say? He caught me with a spinning heel kick to the head.
"I felt good tonight. I felt capable of winning this fight."
Souza impressive in UFC debut, submits Camozzi in first
Souza, the former Strikeforce 185-pound champion, is just too skilled standing. Plus, he was extremely excited to make his first appearance inside the Octagon a memorable one. And he did.
Souza landed a right hand that stung Camozzi seconds into the fight. He later got Camozzi on his back and eventually submitted him. The end came at 3:37 of the first round.
It was an impressive win, the type that had Souza smiling from ear to ear afterward. If he had any Octagon jitters, none were evident.
"When I was about to start in UFC, I was asked if I was going to get the jitters, I said 'no' because of the crowd," said Souza, who improved to 18-3. "We were grappling and I was waiting for him to give me the opportunity and I saw his neck out here and I went for it."
Though outclassed technically, Camozzi fought hard but could not find an answer for Souza, who has won four in a row. Camozzi, who entered on a four-fight win streak, slips to 19-6.
Dos Anjos stands his ground in win over Dunham
Rafael dos Anjos and Evan Dunham put it all on the line in their lightweight battle. Taking a backward step was clearly not part of either man's game plan as they stood toe-to-toe and exchanged strikes throughout most of their three-round affair.
When it was finished, dos Anjos impressed all three judges enough to earn a unanimous decision. Each judge scored the bout 29-28. ESPN.com had Dunham winning 29-28.
Dos Anjos (19-6) got off to a fast start, landing hard right hands that found Dunham's chin often, to the delight of the Brazilian fans. But Dunham withstood the punches.
But in the second, Dunham (14-4) took away some of the momentum by finding his range. With his superior reach, Dunham mixed up his attack beautifully with kicks and punches.
While dos Anjos ate several hard strikes he was able to connect with punches and knees. A knee from dos Anjos, however, was caught by Dunham and he was taken to the ground. Dunham got a second takedown with about three seconds remaining in the round.
With each fighter in position to claim a round, the third decided the outcome. It was Dunham, however, who appeared to be the fresher combatant.
He was quicker to deliver strikes, landing punches and kicks that found dos Anjos bleeding face -- a cut that was opened up in the second round. But dos Anjos landed hard punches of his own, especially a right hand and a kick to Dunham's body.
It was enough to convince all three judges that dos Anjos deserved to have his win streak extended to four.
Natal survives early onslaught to spoil Zeferino's debut
But Natal survived the assault and took advantage of an exhausted Zeferino to earn a unanimous decision.
The judges scored it 30-27, 29-28 and 29-28. ESPN.com had Natal winning 29-28.
Zeferino's early aggression might have been due to the excitement of his UFC debut in his native Brazil. But in the second round Zeferino's adrenaline level decreased. His punches had less pop and he threw fewer. Zeferino also started breathing heavy.
Natal, sensing his opponent was fatigued, took advantage and landed strikes of his own. He also got the better of Zeferino on the ground.
The action slowed noticeably in the third. But Natal (16-4-1) was able to get a takedown, which proved to be the difference. While on the ground, the physically larger Natal dominated to secure his fourth win in five outings.
Zeferino, who entered the bout on a seven-fight win streak, dropped to 13-5.
Lentz pressures Dias to remain unbeaten at 145
But Lentz proved he should be taken very seriously in the featherweight division. Lentz pressured Dias throughout the first two rounds and survived an aggressive Dias in the third to earn a unanimous decision victory.
The judges scored the fight 28-27, 29-28 and 29-28. ESPN.com scored it 29-28 for Lentz, who improved to 24-5-2 with one no contest. He is 3-0 at featherweight.
Dias, who was told by his corner before the start of the third round that he needed a knockout to win, came out throwing hard punches that caught Lentz on the chin and had him moving backward for the first time in the bout.
Later in the round Lentz was able to survive a triangle choke, but he'd eat several more punches from Dias. It was Dias' best round, but he was unable to overcome his two-round deficit.
Dias fell to 21-2-1 as his win streak was snapped at nine.