BOSTON – In what turned out to be a dominant performance, Stipe Miocic retained his title and staked his claim as the most successful heavyweight champion in UFC history.

Miocic (18-2 MMA, 12-2 UFC) had the occasional scare from the favored Francis Ngannou (11-2 MMA, 6-1 UFC) and his power, but after a slugfest of a first round, it was all Miocic against an increasingly exhausted challenger. Miocic won with a trio of 50-44 scores, meaning all three judges gave him a 10-8 round.

With the win, Miocic set the UFC record for most successful title defenses in the heavyweight division with three.

The heavyweight title bout was the main event of today’s UFC 220 card at TD Garden in Boston. It aired on pay-per-view following prelims on FS1 and UFC Fight Pass.

Miocic kicked low early, then ate a body kick from Ngannou. But quickly after, he ducked under and took Ngannou to the canvas. The challenger was up quickly, then backed the champ away with a punch. Miocic again went after a takedown, then found himself scrambling away from the aggressive Ngannou. HE avoided the offense for a moment, then got hit flush with an uppercut. He stayed upright, but 90 seconds in, Ngannou was proving to be the type of offensive threat everyone imagined.

Around two minutes in, Miocic again ducked away from a punch, then pressed Ngannou to the cage. Ngannou pushed out midway through the round, then backed Miocic up againThe champ then landed a big right hand, but Ngannou stayed in the pocket. Shortly after, Miocic landed again, then with two minutes left drove in and took Ngannou down. He quickly moved to side control, then jumped over to reverse mount.

Back in side control, he pounded away with punches and elbows. With 50 seconds left, Ngannou got back to his feet. Miocic had a mouse under his left eye. Ngannou looked fine, and landed a pair of punches. But Miocic winged away with his own and wobbled the challenger, then took him down right before the horn. Ngannou wobbled his way to his corner and looked exhausted.

Ngannou landed a solid right hand 30 seconds into the second, and early on both fighters looked like they were running short on gas after a wild first five minutes. Miocic worked some leg kicks whiel the pace slowed, then slipped away from a winging Ngannou right hand. When Miocic went after a takedown two minutes in, Ngannou stuffed it, but couldn’t land to follow up. Midway through, Miocic landed a right hand that sent the sweat flying from Ngannou’s head.

He followed it up with a takedown, driving Ngannou across the cage. He tried to take Ngannou’s back to look for a choke, but Ngannou got to his feet. Miocic had him in position to land knees, but Ngannou put a hand on the canvas. While he kept the hand there, Miocic stalled and waited. With a minute left, he brought him fully back down and kept landing knees to the body. Ngannou covered up his face to defend from Miocic’s punches, but the champ finished the round stifling him and threatening with a rear-naked choke before the horn.

Quickly into the third, Miocic drove for a takedown, but Ngannou stuffed it. They tied up, and eventually Ngannou tried to throw Miocic to the canvas. But Miocic worked that to his advantage and wound up in the better position with Ngannou up against the fence. The champ punched his face until he got up, then landed a knee to the head that forced Ngannou to put his hand on the canvas again as a defense. Midway through, they broke away from the fence and Miocic landed a right hand. Ngannou hurt him seconds later with his own right, but Miocic pushed ahead and took the challenger down. He got on top of an increasingly wiped out Ngannou and punched away at his head from half-guard. Ngannou was largely defenseless until a minute left, but soon after Miocic continued punching. They weren’t fight-enders, but served to continue wearing Ngannou out.

In the fourth, Miocic took Ngannou down right away and easily got to side control. He worked to isolate Ngannou’s arm, then tried elbows. Punches followed until Ngannou tried to kick out. When Miocic went back down, Ngannou gave his back and started to turtle up from the punches and elbows to the body. Ngannou tried to crawl to the fence, but Miocic stayed blanketed all over him. Ngannou kept hands on the canvas to avoid knees to the head. Ngannou covered up while Miocic kept hammering away with short punhes, but it wasn’t enough for Herb Dean to wave it off.

In the fifth, Ngannou had to know his only hope would be a finish. Miocic struck early to make sure that was a difficult task by clinching Ngannou up and pressing him to the fence. Dean called for action, so Miocic peppered in some knees and tried to trip Ngannou down. Instead, Miocic found himself needing to work out of an Ngannou guillotine choke. He did, then pressed the challenger back to the cage with three minutes left. Midway through the round, Dean split them up and sent them back to the center of the cage. Both looked tired, but Miocic had the perceived edge in energy. Ngannou tried to put together a couple quick punches, but soon was on the receiving end of a Miocic left hand. Somehow, Ngannou mustered the energy for a Superman punch that was off the mark, but with 25 seconds left Miocic tied him up, pushed him to the fence, and that’s where the fight ended.

Miocic won for the sixth straight time. Ngannou had his 10-fight winning streak of stoppage wins snapped.

Up-to-the-minute UFC 220 results include:

• Stipe Miocic def. Francis Ngannou via unanimous decision (50-44, 50-44, 50-44)
• Daniel Cormier def. Volkan Oezdemir via TKO (punche) – Round 2, 2:00
• Calvin Kattar def. Shane Burgos via TKO (punches) – Round 3, 0:32
• Gian Villante def. Francimar Barroso via unanimous decision
• Rob Font def. Thomas Almeida via TKO (strikes) – Round 2, 2:24
• Kyle Bochniak def. Brandon Davis via unanimous decision (29-28, 29-28, 30-27)
• Abdul Razak Alhassan def. Sabah Homasi via knockout (punch) – Round 1, 3:47
• Dustin Ortiz def. Alexandre Pantoja via unanimous decision (29-28, 29-28, 29-28)
• Julio Arce def. Dan Ige via unanimous decision (30-27, 30-27, 29-28)
• Enrique Barzola def. Matt Bessette via unanimous decision (30-27, 29-28, 29-28)
• Islam Makhachev def. Gleison Tibau via knockout (punch) – Round 1, 0:57

For complete coverage of UFC 220, check out the UFC Events section of the site.

(MMAjunkie’s Ken Hathaway contributed to this report on site in Boston.)