UFC

And now ... "Street Fighting Stories with Marlon Wayans!"

This time, Marlon is telling us all about the time someone picked a fight with UFC star Nick Diaz -- and it ended with VIOLENCE!

Marlon was leaving Catch in West Hollywood over the weekend -- where Nick Diaz had also been hanging out -- and it reminded Marlon about the one dumbass who tried to fight the Diaz Brothers in front of him.

"I said 'Brah, you f***ing with the wrong dude.' He goes 'F*** that bro. You don't know me. I'm gonna f*** [him up].'"

Marlon says he TRIED to warn the wannabe tough guy ... to no avail.

"Nick grabbed his ass ... Pop! Pop! Pop! Three elbows. Pop! Pop! Two knees. Fight was over. Blood everywhere."

Matt Serra says his SHOCKING TKO of Georges St-Pierre at UFC 69 in '07 was the real-life version of a 'Rocky' movie -- ONLY BETTER ... 'cause he knocked GSP's ass out!

Serra -- who's gonna be inducted in the UFC Hall of Fame in July -- talked to TMZ Sports about his iconic win ... one most UFC fans consider the most stunning upset in the history of the sport.

In case you forgot ... Serra -- a heavy underdog -- unleashed a fury of punches on the then-welterweight champ ... forcing "Big" John McCarthy to stop the beating in the 1st round.

"I've always said that I really, truly lived my 'Rocky' movie with that fight." Serra told us.

Dana White says the UFC will not mete out punishment for Conor McGregor's bus attack until AFTER the New York City judge issues a ruling ... which means it could take a while.

McGregor isn't due back in court until June 14 -- and Dana tells TMZ Sports he's very interested in how the law treats the Irish superstar.

McGregor is reportedly facing up to 7 years in prison for the April 5 attack in which he threw a dolly at a UFC bus, shattering glass and injuring several UFC fighters.

"He's gotta be punished by the law first," White says ... "Let's see what happens in New York."

As for Conor's fighting future ... White says if he does ever fight Khabib Nurmagomedov, it will NOT go down in Russia.

"If you do a fight that big, you gotta do it in Vegas."

"Khabib will fight in Russia at some point, but it wont be that fight. It's too big. Ya gotta do it in Vegas."

Ali, Marciano, Tyson ... when it comes to great runs in boxing, Floyd Mayweather beat 'em all -- so says Dave Chappelle.

FYI, Dave is a HUGE boxing fan -- and has attended a bunch of Floyd's fights in person.

So, when we saw the comedy legend out in L.A., we had to ask about Mayweather -- and if he supports Floyd possibly jumping into the Octagon.

"I think Floyd had a great record and the greatest run in the history of boxing," Chappelle said ... "I don't know, whatever makes him happy, but I think he did his thing."

Floyd's run was legendary ... he was a champ in 5 different weight classes and made more money than any other athlete on the face of the planet.

Also, his fights have generated more money in PPV sales than any other fighter in history.

Tyron Woodley is begging Kanye West to STOP supporting Donald Trump ... saying his pro-POTUS tweets are "a poor way of getting attention."

The UFC champ went off on Ye on "The Hollywood Beatdown" -- suggesting Kanye is diabolically using the controversy to drum up interest in his albums.

Woodley also weighs in on rumors Kanye will run for office one day ... telling the rapper the only way he should be running is if he's on a treadmill!

Woodley also weighs in on Greg Hardy getting a shot in the UFC and talks about Odell Beckham's SUV pulling workout!

Ronda Rousey believes it is a privilege to hear her speak ... and she means it.

The UFC legend was promoting her movie "Mile 22" when she was asked why she's dialed back her interactions with reporters ... something she didn't used to do when her UFC career was on the rise.

"We live in an age of trial by Twitter,” Rousey said ... "What is really gained by stating opinion on anything? It whittles people down. It gets cut and pasted 10 times and it’s in a headline."

"Why should I talk? I believe hearing me speak is a privilege, and it’s a privilege that’s been abused, so why not revoke it from everyone?"

"I don’t believe public criticism beating you down is the right thing to do.”

Rousey also offered an explanation for why her 2 final UFC losses were so hard for her to handle publicly.

Nick Diaz says the Floyd Mayweather shooting was "f*cked up" -- especially because he knows a couple of guys in Floyd's entourage who were in the van during the attack.

"That was my boy that got shot I think," Diaz said before sending a message to the guy -- "I hope you feel better, you got shot."

As we previously reported, Mayweather's longtime TMT bodyguard, Greg La Rosa, was hit in the leg when a gunman ambushed Floyd's crew in Atlanta. Greg is recovering and should be okay.

Diaz said there's really nothing Mayweather's team could have done to prevent the shooting -- explaining, "Sometimes it's just gonna go down."

"When it goes down, it goes down."

If Greg Hardy fights his way into a UFC contract, one of the biggest stars in his division wants a piece of the ex-NFL star ... with Derrick Lewis saying, "I like knocking wife beaters out."

Hardy is reportedly getting his shot during the UFC Contender Series -- in which up-and-coming MMA fighters compete for a chance at a UFC contract. It's where UFC star Sean O'Malley got his start.

Hardy (who's 3-0 as an amateur) would obviously compete in the heavyweight division -- where Derrick "The Black Beast" Lewis is ranked #6 in the world.

So, how does Lewis feel about a potential showdown somewhere down the line?

"He's a wife beater ... I'd like to get in there with him."

Lewis is referring to Hardy's domestic violence case -- in which he was initially convicted of attacking his then-girlfriend. The conviction was later thrown out when the alleged victim stopped cooperating with prosecutors.

Still, Lewis ain't letting Hardy off the hook.

"I'll fight Greg Hardy ... It'll be like vice versa him beating on a woman. I'll be beating him like he was a woman."

Why so much animosity?

"I grew up watching my mom and my stepdad fight," Lewis says ... "Fistfighting every day for stupid stuff. I don't tolerate stuff like that at all."

First things first ... Lewis has a brawl with Francis Ngannou lined up at UFC 226 on July 7 ... about a month after Hardy gets his UFC shot.

Stay tuned ...

UFC badass Max Holloway doesn't get taken to the ground very often ... but he got BLOWN UP by a military attack dog in South Korea -- and the whole thing was caught on video.

Max -- along with stars like Paige VanZant, Jon Stewart and Rip Hamilton -- are out in Asia visiting U.S. military personnel as part of a USO tour.

One of the activities ... testing your mettle against the dogs (just like Mark Ingram did earlier this month).

Things didn't bode well for Max ... but ex-NBA star Rip hung in there surprisingly well!

Props to the entire group for sacrificing their bodies for the entertainment of our troops!

Not exactly the homecoming Conor McGregor imagined ...

The UFC star has finally returned to Ireland after that violent bus attack in Brooklyn ... but instead of soaking up the spotlight (as usual), he shot photogs the 1-finger salute.

As we previously reported ... after McGregor was released from jail on April 6, he flew to the Bahamas for a little R&R with his girlfriend, Dee Devlin, and his kid, Conor McGregor Jr.

But now, Conor has returned back to Ireland ... and he doesn't look too happy.

Maybe it's because he's due back in court in Brooklyn in June ... or because some of his fellow countrymen feel he brought great shame on his country.

Ronda Rousey's first wrestling match wasn't just great, it was the GREATEST OF ALL TIME -- so says WWE Hall of Famer Jim Ross.

Good ol' JR was at WrestleMania 34 to watch Ronda take on Stephanie McMahon and Triple H up close and personal ... and told us he's never seen anyone dominate the squared circle this fast.

"I thought Ronda Rousey's debut was the most impressive thing I've seen in pro wrestling in my 40-year career ... best debut I ever saw," JR told TMZ Sports.

JR also gave WWE mad props for pickin' up the UFC mega-star -- calling it the 2nd best hire they've ever made besides him (lol), and saying she's a "huge star" for the company.

UFC fighter Brad Tavares is doubling down on his weekend call-out of Michael Bisping ... telling TMZ Sports the ex-champ is ducking him 'cause he's terrified of getting THRASHED.

"I think he’s scared ... scared to get his ass beat," Tavares said. "What else could it be?"

FYI, the Hawaiian went looking for Bisping backstage after he merked Krzysztof Jotko at UFC on FOX 29 ... to call out the UFC legend for his retirement fight.

Bisping LOL'd at Tavares' challenge -- telling the top-10 middleweight to "get the f**k out!"

But, Brad ain't giving up -- saying there's no better option for him unless he's gunnin' for Conor McGregor (yeah ... ain't gon' happen).

Conor McGregor's lucky UFC star Kevin Lee wasn't in the bus he attacked -- 'cause if he was, K-Lee says he would've gone full Dark Knight on his ass!!

"It would have been totally different -- totally different story," Lee told TMZ Sports. "I would have jumped out like Batman when he threw the dolly through."

Kevin doesn't give a damn Conor was flanked by a full goon squad -- saying all of McGregor's wannabe gangsters would've tasted his hands.

But, "The Motown Phenom" doesn't want Conor to leave the UFC ... 'cause he wants that "easy money" fight inside the Octagon!

But, before Kevin tries to win the McGregor sweepstakes, he's got a date with nasty striker Edson Barboza at UFC Fight Night: Atlantic City this Saturday ... and he told us why it's gonna be fireworks.

Tekashi69 needs to be careful ... because if his feud with Adrien Broner turns into a REAL fight, Broner would knock his ass out in ONE PUNCH -- so says Tyron Woodley.

Tyron was trying REALLY hard to warn Tekashi on "The Hollywood Beatdown" that his hands aren't on the same PLANET as Broner when it comes to fighting ... and the proof is in that weak ass LAX brawl earlier this year.

In fact, Tyron says Broner needs to ignore 6ix9ine and focus on his REAL business -- beating Jessie Vargas at the Barclays Center in Brooklyn on Saturday night (live on Showtime).

There's more ... Tyron also reacts to a videotaped message from Daniel Cormier about his fighting future.

Plus, Woodley rips Danielle Bregoli, Woah Vicky and Lil Tay for that stupid YouTube star brawl in L.A.

UFC fighter Aljamain Sterling loves to rage -- so once he's done kickin' ass inside the Octagon this weekend, he says he's gonna TEAR UP Atlantic City with his boy, Al Iaquinta!!

“Oh yeah ... we’re going to be getting into some trouble. We’re ragin'! Ragin'!” Sterling told TMZ Sports ahead of his UFC Fight Night 128 bout with undefeated Brett Johns.

If ya hadn't heard, Iaquinta got hammered and wrecked his hotel room after winning at UFC 183 ... and Aljamain says Round 2 would've happened if Ragin' Al upset Khabib at UFC 223 earlier this month.

Instead, he took an L -- but Aljo says they'll party on after he beats Johns in their own backyard (they're Jersey bros).

Aljo also told us why Iaquinta steppin' up vs. Khabib inspired the hell outta him ... and changed the way he's approaching his fights.

Daniel Cormier says the clock is ticking on a Jon Jones rematch ... 'cause he's retiring when he turns 40 (next March), period.

We got the UFC light heavyweight champ on the "TMZ Sports" TV show ... and asked if there was any way he'd make an exception for his hated rival -- who could be on the shelf past then 'cause of his steroid suspension.

"If I'm not gonna do it for guys that I really like, I won't do it for somebody that I don't like," Cormier said. "So, if he doesn't come back before that date, our time will have passed."

DC also told us why Conor McGregor wouldn't stand a chance against his boy, Khabib ... and why ya gotta tune in to him and Stipe Miocic (a guy he likes waaaaay more than Jones) coaching this season of 'The Ultimate Fighter.'

Catch the full interview with Cormier -- and the premiere of 'TUF Season 27' -- Wednesday night on FS1!