Of course Floyd Mayweather took care of business last night against Miguel Cotto -- he had the dreaded masters of intimidation in his corner, like Lil Wayne, 50 Cent and ... Justin Bieber?

Bieber walked out with Mayweather before the fight and was in the ring with him after to celebrate the victory. 

It's unclear how the two hooked up, though Bieber did once compare himself to Mayweather in an interview. Earlier in the day, Bieber tweeted, "cinco de mayo.... #MayweatherCotto yeah @FloydMayweather today is a BIG day."

So we have to ask ...

50 Cent is being accused of sampling a song without permission on an album he released for free online nearly three years ago -- and the guy suing claims 50 knows he took the song ... but just doesn't care!

According to a lawsuit filed in New York, Robert Poindexter of The Persuaders claims 50 used a snippet from his band's song "Love Gonna Pack Up and Walk Out" on a song called "Redrum."

The song appeared on an album that 50 posted online for free ... which Poindexter claims 50 feels gives him immunity from any copyright claims.

Poindexter says in the suit, "Fifty Cents [sic] has not denied the infringement, but appears to be basing his defense solely on a frivolous and immaterial claim that the illegal version is not being commercially exploited, but is given away for free."

Free or not, Poindexter is suing for unspecified statutory damages and an additional $600,000 in punitive damages, plus interest. 

Calls to 50's people were not returned.

Joan Rivers could barely keep a straight face when she got up close and personal with music mogul 50 Cent in NYC on Tuesday.

It what could be the makings of the new "Odd Couple," the 78-year-old comedian even got a peck on the ear from Fiddy at a shoot for his Street King energy drink.

Forget can we tawk ... can she rap?

50 Cent's performance on "X-Factor" last month was a bloody mess behind the scenes -- with one stagehand smashing his head open after falling off the stage ... this according to the 911 call obtained by TMZ.
 
The accident occurred just as Fiddy took the stage to perform two songs (below). According to reports, a stair riser crashed down on several stagehands ... striking two on the head and one on the elbow.



As a result of the accident, according to the 911 call, one man fell off the stage and "cracked his head open."

Paramedics responded to the scene, treating the injured just feet away from 50 Cent's performance. All three stagehands were rushed to a nearby hospital for treatment.

50 Cent is telling friends ... there's a reason he was laughing his ass off at Ray J and Fabolous -- their little Twitter feud was like a fight between two school girls.

We posted video of the Vegas "brawl," which shows Fiddy standing in the background grinning as Ray J and Fabolous went at it.

Sources close to Fiddy tell TMZ, contrary to what some witnesses are saying, the rapper didn't egg Ray J and Fabolous on.  He just couldn't believe they were seriously arguing over Twitter.

Days after the fight, Ray J was still taking himself way too seriously in Vegas -- telling us, "I'm not that proud of nothing that happened."



Fact is ... rapper feuds over Twitter kinda ruins the whole street cred thing.

So we ask ...

TMZ has obtained footage of the Vegas nightclub brawl between Ray J and Fabolous -- and the wildest part ... sources tell us, 50 Cent stirred up the whole thing.

We're told Fiddy had been encouraging Ray to confront Fabolous about their recent Twitter feud -- and Ray finally decided to get in Fab's face at Moon nightclub inside The Palms casino.

In the clip, you can see 50 standing between Ray and Fabolous ... with a big ass grin.

But we're told Fiddy actually jumped in to break things up when Ray J and Fab started scrapping.

As we previously reported, Ray J was booted from the club after the fight -- but he was not arrested.

50 Cent employs violent known criminals who viciously attack women when they don't get their way ... this according to a new lawsuit.

According to the suit, obtained by TMZ, 50 Cent hired a guy named Dwayne McKenzie -- although it's not clear exactly what McKenzie did for the rapper.  The suit alleges McKenzie invited some women over to 50's mansion in Connecticut.  During the party, McKenzie began making "graphic and vulgar sexual requests" of one woman.

The plaintiff, Vasti Ortiz, apparently became uncomfortable and started to leave.  She claims that's when McKenzie ordered another woman to start beating on her while he held her down ... badly hurting her.

So why is 50 being sued, aside from the fact that he's rich?  Ortiz claims 50 knew or should have known McKenzie was a known criminal who had assaulted in the past.

50 was not present during the alleged attack.

Pauly D is DANGEROUSLY close to joining forces with G-Unit -- because TMZ has learned, 50 Cent desperately wants to sign him to his record label ... in fact, a 3-album deal is already on the table.



Sources close to negotiations tell TMZ, the "Jersey Shore" DJ met with Fiddy and his people in NYC last week -- where they discussed the lucrative record deal ... and also tossed around the idea of a Pauly D merchandise line, specifically Pauly D-brand headphones.

Nothing's signed yet -- but according to sources, 50 wants to hammer out the deal ASAP ... before Pauly jets off to Italy to shoot "Jersey Shore" Season 4.

We're told talks have become so serious -- 50 and Pauly have even started to kick around ideas for people Pauly can collaborate with. Calls to 50's people weren't returned.

50 Cent created a security nightmare for the people handling a SMALL "Scream 4" afterparty tonight ... when he passed along the event details to a few MILLION people.




TMZ has learned ... 50 and the Weinstein Brothers are co-hosting the party at a restaurant in NY tonight ... an event that was only supposed to cater to roughly 100 people.

But event organizers freaked out when they noticed 50 posted the invitation on his Twitter page -- because 50 has 4 million followers ... and they now have to prep in case an army of fans try to crash.

According to Mike Zimet, event security specialist for the Weinstein Company, additional security has already been called in... because, "While we appreciate 50's enthusiasm, we are not quite prepared in the event that his 4 million followers turn up."

Dr. Dre totally DISSED his former protege 50 Cent in Los Angeles the other night ... maybe ... possibly ... OK, we're really not sure -- but it's all on tape!!!!


Here's the back story -- 50 went on a Twitter tirade this week, claiming Dre HATES him because he's launching a line of headphones to compete with Dre's "Beats" line.

But when we asked Dre about the beef out in front of Boa Steakhouse in Hollywood Tuesday night ... Dre simply replied, "I never heard of his headphones."

DISS!!!!!!!!!!!! (maybe). Check out the video.

The guys who were arrested inside 50 Cent's Connecticut mega-mansion weren't trying to steal anything -- they just wanted to get hammered in the lap of luxury ... at least that's what they're telling people.



TMZ spoke with the sister of Alexander Hernandez -- the guy who was found drinking wine in Fiddy's closet when cops arrived yesterday -- who tells us Alexander is claiming he and the other suspect just wanted to "hang out" at 50's place because they're both huge fans.

She adds ... Hernandez is claiming he never tried to steal anything from inside the house -- they only wanted the "thrill" of getting inside.

As we previously reported, cops say both men were inside Fiddy's pad -- and in possession of weed -- when police responded to the home.

Alexader's sister also tells us family members are concerned about her brother -- because he's still in police custody and could possibly miss his newborn baby's first Christmas.