LAS VEGAS (AP) — Israel Adesanya learned that holding two UFC title belts simultaneously is not nearly as easy as Amanda Nunes makes it look.

And Petr Yan learned that even a momentary lapse in discipline can dearly cost a champion.

Jan Blachowicz defended his UFC light heavyweight title with a unanimous decision over the previously unbeaten Adesanya at UFC 259 on Saturday night, thwarting the reigning middleweight champ's bid to claim a second belt.

Two-division champion Nunes defended her featherweight belt with ease, beating Megan Anderson by submission 2:03 into the first round at the Apex gym on the UFC’s corporate campus. Aljamain Sterling also won the UFC's bantamweight title when Yan was disqualified for an illegal knee strike in the fourth round.

The 38-year-old Blachowicz (28-8) made his first title defense in impressive style by outworking Adesanya (20-1), the fearsome 185-pound champion moving up for a shot at history. The Polish champion used his size advantage and veteran savvy, taking control of their fight with two huge takedowns and subsequent ground control in the fourth and fifth rounds.

Blachowicz won 49-46 on two judges’ scorecards and 49-45 on the third. The Associated Press scored it 48-47 for Blachowicz.

Blachowicz ended the fight in full mount while raining down punches on Adesanya, who had never lost in a mixed martial arts career that began in 2012. The charismatic Nigerian-born New Zealander failed to join Nunes, Conor McGregor, Daniel Cormier and Henry Cejudo as the UFC’s only simultaneous two-belt champions.

Adesanya took his first setback in stride.

“Losses are part of life,” Adesanya said. “This is just my first one in MMA. If I was going to lose to anyone, what better guy to lose to than a guy like Jan? Classy champion, cool dude, nice guy. He has a great story to tell. From almost getting cut from the UFC, he becomes a champion and hands this guy, a future legend, his first loss.”

Adesanya appeared to be the sharper, more aggressive striker in the early rounds, but Blachowicz countered the onslaught with his own strikes and eventually implemented his game plan. Blachowicz turned the fight in the fourth round with an impressive takedown and strong ground work, all but forcing the judges to give him the round.

He took down Adesanya again midway through the fifth before ending the fight in a dominant position. Blachowicz joyously celebrated the latest victory in a late-career surge for a fighter who won his title last September after six years in the UFC and 13 years as a pro.

Nunes (21-4) handled her second featherweight title defense with her usual flair, making short work of her Australian challenger while extending her winning streak to 12 fights since 2014. After peppering Anderson (11-5) with strikes, Nunes jumped on her off-balance challenger and worked her way into a triangle armbar, forcing Anderson to tap out quickly.

The fight was Nunes’ first since her wife, fellow UFC fighter Nina Ansaroff, gave birth to their first child. Nunes has been the UFC’s bantamweight champion since 2016, and she added the featherweight strap in late 2018.

“Since my daughter was born, it’s the best thing that happened in my life,” Nunes said. “She’s made me a better person, more happy. The house is full of love. She was supposed to be sleeping tonight, but she waited and waited to watch my fight, and now she’s sleeping. I’m glad that I shined for her.”

The much-anticipated slate of three championship fights at UFC 259 got off to a bizarre start when Yan's inexplicable rules violation handed the 135-pound title to Sterling, the first fighter to become a UFC champion on a disqualification.

The fight was stopped with 31 seconds left in the fourth when Yan drove his knee into the face of Sterling, who was kneeling on the canvas in front of him.

MMA rules strictly prohibit such blows to a downed opponent, and the knee clearly hurt Sterling, who struggled and failed to get up for several minutes. The bout was called off by referee Mark Smith, who had verbally warned Yan not to throw such a strike a few seconds earlier.

Sterling (20-3), a Long Island native, appeared disoriented and disappointed when the belt was wrapped around his waist after a fight he appeared to be losing to Yan (15-2). Sterling threw the belt onto the canvas before he left the octagon.

“Everything I worked for to this point, and to have the fight go like that ...," a teary-eyed Sterling said afterward. “I thought the fight was very close. I thought I was down two rounds. That’s not the way I wanted to win. That’s not the way I envisioned this. I just took the belt off, man. I was trying to continue, but I was in bad shape.”

Earlier, former bantamweight champion Dominick Cruz beat Casey Kenney by split decision for his first victory since June 2016. Cruz, who turns 36 on Tuesday, saw his ascendant career derailed long ago by brutal injury problems, but he persevered against a similarly exhausted Kenney to win in just his sixth MMA bout since October 2011.

Three-time flyweight title contender Joseph Benavidez also took his third consecutive loss in a one-sided decision win for Russia's Askar Askarov, who missed weight for the bout.

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