Cormier moved forward like a land shark in the early rounds. But Jones looked fresher in the fourth and fifth rounds, controlling the tired challenger and blunting his arsenal.
All three judges scored it 49-46 for Jones, who made his eighth straight successful title defence. FightMetric had Jones leading Cormier 92-58 in significant strikes, connecting more in every round but the second.
"All the crap (Cormier) talks, it motivated me," Jones said after the fight while wearing a T-shirt that read "Unbroken."
"I do not like DC," he added.
Said Cormier: "I know I lost and Jon won."
Both fighters were classy at the post-fight news conference, with Cormier wiping away tears as he said he would be back.
Jones (21-1) and Cormier (15-1) each earned US$50,000 bonuses for fight of the night.
The bad blood between the two made the showdown one of the UFC's most anticipated in recent memory. UFC president Dana White said the card drew more than 750,000 pay-per-view buys. The arena gate was $3.7 million.
Jones' immediate future is a date with the winner of the bout between No. 1 contender Alexander (The Mauler) Gustafsson and No. 3 Anthony (Rumble) Johnson. After that, there aren't too many challenges left in the division.
In the co-main event before 11,575 at the MGM Grand Garden Arena, veteran lightweight Donald (Cowboy) Cerrone schooled the previous unbeaten Myles (Fury) Jury in a unanimous (30-27, 30-27, 30-27) decision.
Cormier, wearing a T-shirt saying "King of the Grind," walked out first to "Right Above It" By Lil Wayne and Drake. His cornermen wore "Break Bones" T-shirts.
The challenger entered the cage to cheers.
Then came Jones, a champion who has yet to win over many fans despite his dominance in the cage. He came in to mostly boos and a mix that included Nelly's "Hot in Here" and "The Champ is Here" by Jadakiss.
Cormier paced in the cage as the relaxed champion, showing a few dance steps along the way, entered the arena. Burly security officials kept themselves between the two 205-pound fighters before the introductions.
The two touched gloves, after a brief delay, and then went at it.
The five-foot-11 Cormier, ranked second among light-heavyweight contenders, was giving up five inches in height and 12 in reach.
Cormier said he would come right at Jones and he did. But Jones gave as good as he got, kicking Cormier's feet out from under him.
They exchanged blows in the clinch. When they separated, Jones scored with body punches. The champion thrust his arm in the air as the round ended.
In the second, Jones stuffed a takedown. Cormier continued to go for the clinch, blood oozing from his face as he tried to dirty-box Jones, who countered with short elbows. The crowd chanted DC as the challenger got Jones' attention with uppercuts.
"Use your wrestling with the dog-fighting," Cormier's coach Javier Mendez yelled between rounds.
Cormier was poked in the eye in third, promoting a delay. The crowd booed as they saw the replay of Jones' hand in Cormier's face. Jones apologized.
Again, the action was intense and often in-close. Cormier scored with blows near the end of the round, with Jones pulling guard as it ended.
Jones took Cormier down twice in the fourth at the fence, the first takedowns in Cormier's UFC career. He eventually got back up but looked tired as Jones leaned on him. The champion began to control the clinch and dumped Cormier on his back as the round ended.
Cormier turned it up as the fight ended. He picked Jones up and slammed him to the canvas in the final minute but the champion got right back up.
Jones converted three of five takedowns while Cormier, a former Olympic wrestler, was one of eight.
Referee Herb Dean had to separate the two as the horn sounded, with Cormier seemingly launching a late punch. Jones put his arms in the air, while an exhausted Cormier leaned against the fence.
Both men came into the fight unbeaten, although Jones has a loss by disqualification on his record. That came in December 2009 for an illegal elbow that was thrown when opponent Matt (The Hammer) Hamill was beaten and broken.
The two fighters came to blows at a news conference in August, a melee that left a security official with a broken rib and both fighter facing fines and community service. The bad blood has continued to boil since their first meeting, when Cormier insisted Jones disrespected him. Jones disputes that view, saying Cormier took offence at a joke.
While the two kept their cool at Friday's weigh-in, the war of words continued backstage.
The 27-year-old Jones stepped into the cage having ruled the 205-pound division for 1,386 days, a record in the weight class. He had won 11 straight, the longest active streak in the UFC.
The 35-year-old Cormier, who won the Strikeforce heavyweight Grand Prix tournament, came into the bout having outstruck all his opponents in the UFC and Strikeforce.
The 31-year-old Cerrone, ranked fourth among lightweight contenders, came into the fight having won five in a row. No. 8 Jury had won six straight in the UFC.
Jury took Cerrone down early but found himself in deep water after Cerrone, following an omoplata submission attempt from the bottom, reversed position and took Jury's back. Jury fought off a rear-naked choke and then an armbar as the round ended.
Cerrone (26-6 with one no contest) stalked Jury for the next two rounds, lashing him with kicks while stuffing takedowns. He landed a head kick on Jury (15-1) in the third, drawing oohs from the crowd.
Jury finished the fight on his back, eating eight vicious leg kicks from Cerrone, who clearly wanted to make a statement against the highly touted 26-year-old.
Welterweight Hector Lombard, a 12-1 favourite, won a unanimous (30-27, 30-27, 29-28) decision over Josh (The People's Warrior) Burkman, who took a pounding as the bout wore on. Burkman's right leg looked like someone had taken a hammer to it.
The 36-year-old Lombard, a five-foot-11 slab of muscle ranked sixth among welterweight contenders, competed for Cuba in judo at the 2000 Olympics. Lombard (35-4-1 with one no contest) showed a lot of tools and savvy in handling Burkman.
Burkman's last outing in the UFC was in 2008. The 34-year-old from Utah went 9-2 outside the organization to earn his ticket back against a fighter that few wanted to face.
Burkman (28-11) backed himself in the fight, betting US$1,000 that he would stage the upset. Had he disposed of Lombard, he would have gone home some $5,000 richer, money he planned to use to start a college fund for a second son due Jan. 10.
"I had the worst camp of my life," said Burkman. "I sprained my ankle, I hurt my hip, dislocated a rib and got sick so I had to go on antibiotics. But I'm a man of my word and I signed to fight Hector Lombard and that's exactly what I did."
The UFC allows fighters to bet on themselves to win.
After the fight, Lombard said he would like to fight Canadian Rory MacDonald next.
Japan's Kyoji Horiguchi, ranked 11th among flyweight contenders, put on a crisp performance in dispatching Louis (Goodnight) Gaudinot (6-4 with one no contest) via a unanimous (29-28, 30-27, 30-27) decision. Horiguchi (15-1) extended his winning streak to nine, including four straight in the UFC.
Brad Tavares (13-4) handled veteran middleweight Nate (The Great) Marquardt (36-13-2) with relative ease in winning a unanimous (30-27, 30-27, 30-27) decision that did not merit the boos from the crowd.
Tavares peppered the 35-year-old Marquardt, a former Strikeforce welterweight champion who is back at 185 pounds, with jabs and kicks in an impressive outing. Marquardt's left thigh was covered by ugly red welts after his 18th UFC fight.
There were impressive performances on the undercard from lightweight Paul (The Irish Dragon) Felder and bantamweight Cody (No Love) Garbrandt.
Felder (10-0) knocked out veteran lightweight Danny (Last Call) Castillo (17-8) with a spectacular spinning back fist at 2:09 of the second round. Castillo, knocked out cold, eventually had to be helped onto a stool.
He earned a $50,000 bonus for performance of the night.
Felder, from Philadelphia, won a split decision over Canadian Jason Saggo in Halifax last time out.
Garbrandt (6-0) knocked out Marcus (The Bama Beast) Brimage with 10 seconds remaining in an all-action 135-pound fight.
The 23-year-old Garbrandt, who went 32-1 as an amateur boxer, floored Brimage (7-4) with a left and a right in the third-latest stoppage of a three-round UFC bantamweight fight. He said later he thought he broke his hand in the first round.
Heavyweight Shawn Jordan also picked up a $50,000 bonus for performance of the night in a KO win over Jared Cannonier.
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