UFC 239: Jon Jones and Amanda Nunes retain their titles in Las Vegas

Jones extended his record to 25 wins from 26 fights

Two of the UFC's most dominant champions Jon 'Bones' Jones and Amanda 'The Lioness' Nunes successfully defended their titles on a spectacular night at UFC 239 in Las Vegas.

Jones claimed victory in the main event to register the 25th win of his MMA career as he outpointed power-punching Brazilian challenger Thiago Santos after five tense rounds at the T-Mobile Arena.

Former middleweight campaigner Santos, 35, had earned his shot at light heavyweight gold with an impressive hat-trick of stoppage wins after moving up to the 205lb division. And the Brazilian was a constant threat throughout the contest with his powerful punches and kicks.

And when the scorecards were totalled at the end of their 25-minute battle, the judges were split on the result, with the scorecards reading 47-48, 48-47, 48-47 in the defending champion's favour.

"Boy, was he tough," Jones, 31, said after the fight.

"We all knew Thiago's best chance was to knock me out. I played it smart and brought home this gold for my family and team.

"He was technically a lot more sound than I thought. Thiago Santos is a black belt in Muay Thai. I'm proud of myself, because I stood with a guy who's been kickboxing way longer than me."

The night also saw the fastest knockout in UFC history as the previously undefeated Ben Askren was floored after five seconds in his welterweight fight with Jorge Masvidal.

Nunes delivers familiar finish to retain title

Nunes is the first woman to own UFC belts in two different weight classes

In the co-main event title fight, Nunes cemented her legacy as the greatest female fighter in UFC history by defeating former world champion Holly Holm to complete a set of victories over every woman to have ever held UFC championship gold at bantamweight or featherweight.

Holm, 37, previously captured the UFC women's bantamweight title when she knocked out Ronda Rousey with a stunning head kick at UFC 193 in 2015, and the American had high hopes of defeating Nunes and recapturing the title once again.

But Brazil's Nunes had other ideas, and turned to Holm's signature move to secure a spectacular first-round victory. The 31-year-old connected perfectly with a head kick that landed flush, dropping Holm to the mat. A couple of follow-up ground strikes were all that were needed to put the seal on an eye-catching stoppage win.

"People say what happens in Vegas stays in Vegas, but this belt is going home with me," she said.

"During my warm-up, I knew I was going to get her. I told my coaches I wanted to knock her out the same way she knocks people out ... I did it tonight. She was the only former champion I hadn't beaten yet. Now, I've beaten her and I'm very happy."

Masvidal KOs Askren to set new UFC record

Askren (on the floor) suffered the first loss of his MMA career as his fight with Masvidal lasted just five seconds

Welterweight contender Masvidal spectacularly handed Askren the first loss of his MMA career with a jaw-dropping flying knee that knocked out the former Bellator and ONE world champion right at the start of their eagerly-anticipated main card grudge match.

Masvidal, 34, exploded out of his corner and immediately launched himself through the air, connecting flush with his fellow American, knocking him out cold.

Timed at just five seconds, the finish set a new mark for the fastest knockout in UFC history Masvidal staked his claim for a shot at the UFC welterweight title held by Nigerian Kamaru Usman.

"I really wanted to beat him up for 14 minutes and 30 seconds before ending him, but it didn't happen," said Masvidal.

"I have nothing nice to say about him. He was talking wild and I had to show him there are consequences. You're welcome for ending that dude.

"I'm coming for that belt. You know who deserves that belt. I deserve that next title shot. After this performance, I don't want to say anything. I'll let the fans do the talking. They pay guys to fight. if you want to see a fighter, and not someone on social media talking about fighting, that's me."

Blachowicz flattens Rockhold

Polish light-heavyweight Jan Blachowicz delivered a spectacular statement with a crushing second-round knockout of former UFC middleweight champion Luke Rockhold.

American Rockhold, 34, was making his debut at 205lbs after moving up from middleweight and mocked Blachowicz for supposedly having small feet during their media day face off.

But Blachowicz, 36, had the last laugh when he knocked out Rockhold with a colossal left hook, then pointed to his feet in celebration.

"Trash talk doesn't work on me," he said after his win.

"I have the legendary Polish power and I'm proud of it. I saw that left hook in my dreams. I saw it when I visualized the fight. I don't know how many times I watched his fight with Michael Bisping (which Rockhold lost via left-hook KO), but I knew I would finish him similarly."

Allen impresses in Melendez win

It was a big night, too, for English featherweight Arnold Allen, who produced the best performance of his UFC career to claim a shutout win over two-time former Strikeforce lightweight champion Gilbert Melendez.

Allen, 25, dominated the 37-year-old American from start to finish in their featured preliminary bout to earn scores of 30-27 from all three judges and extend his win streak to six. The only featherweight in the UFC with a longer active win streak is the world champion, Max Holloway.

"It went exactly how I expected it," Allen said.

"I knew it would be a full battle, but that I'd be too fast and technical for him. I want to finish guys, but he's as tough as they come."