Beautiful Beyoncé Knowles (27) is the soul singer with the looks, the voice like cream in coffee and the perfect marriage to Jay-Z. And apart from her mega-hits such as Crazy in Love, Beyoncé is known for her political correctness and sheer niceness.

She even serenaded President Obama and friends with At Last at the inauguration ball, showing total class.

Now Beyoncé fans should prepare for a shock. In her new movie Obsessed, the diva of decorum lets her hair down big time in her role as trophy wife of a man stalked by a sexy co-worker.

And Beyoncé admits she enjoyed shaking off that nice girl image. She says: “I’m always so politically correct and I’m always so nice and positive, it was great to let out that aggression.”

She certainly succeeded, and had to engage potential love threat Ali Larter in a superb catfight. The fur really flew as the women got into the punching match, and Beyoncé, who took boxing lessons for the role, reveals that it wasn’t just acting.

The feisty star says: “I was absolutely throwing real punches, and I’ve been taking boxing classes so I used some of my boxing training in the movie.

“And literally I think I scared Ali because she was like, ‘Okay! I thought you were always quiet and calm’. In between takes, I was like ‘Grrrrrr’ and getting myself pumped up and sweating. I was really, really going for it, I was really bruised up and I wanted more blood.

“I loved doing the fight scenes because they were kinda similar to choreography.”

Her co-star Ali, who tries to wring her neck in the scene, wasn’t just terrified, she was overcome with admiration — “And Beyoncé did it all in 4ins heels!”

Watching the women grapple, it’s hard to imagine that Beyoncé has no fighting background.

Unsurprisingly, the singer comes up with a memory of a fight in school, when she was growing up in Houston, Texas.

Beyoncé admits: “Although this was my first fight scene, when I was really young I had a little fight. But I was like in elementary school so I don’t think that really counts. But I won the fight, yes, thank God.”

The school in question was Parker Elementary School, a so-called music magnet school for talented kids. Beyoncé showed early star quality and was a soloist at her church, St John’s United Methodist Church.

Music may have been in her blood, as her African-American father Mathew Knowles was a record manager, while her Creole mother Tina Beyoncé was a costume designer.

The unusual Christian name —her middle name is Giselle — came about so her mother’s family name would be passed down.

Beyoncé’s own marriage, to the rapper-mogul she’d been seeing for six years, took place in some secrecy in April 2008.

It was a glamorous affair, with 75 bouquets of cream and white orchids delivered to Jay-Z’s Manhattan apartment which looked “like a palace”, according to the florist. Among the guests were Gwyneth Paltrow and Coldplay’s Chris Martin.

And although the singer doesn’t readily talk about her private life, the couple had matching eternity ring tattoos just before tying the knot.

Her marriage is famously strong. Beyoncé says, sounding like the cat who swallowed some dairy products:“I’m very happy. I’m happy to have the support of all the people I love. That’s all I’ll say.”

Asked about whether she prefers Jay-Z the businessman or the rapper, she answers: “That’s a good question. I can’t compare because when Jay is really focused he is a brilliant businessman, but he’s the best rapper ever in the world. So it is hard to say. I love both of them!”

Previous roles for Beyoncé, who branched out into acting after leaving Destiny’s Child and starting her solo career, include Foxxy Cleopatra

in Austin Powers in Goldmember and Xania in Pink Panther.

It’s rumoured that Beyoncé would like to be the first black Wonder Woman.

She comments:“That would be cool — but it’s weird because the second someone asks ‘What do you want to do?’ I can answer, ‘Well, I just did two dramas I want to be a superhero now — maybe something like Wonder Woman’.

“Then I open the papers and it says, ‘Beyoncé says she wants to be the first black Wonder Woman’. I’m like, ‘What?!’”

As well as acting and singing, Beyoncé has launched a range of women’s clothes with her mother, House of Dereon, partly as a tribute to her grandmother who was a seamstress. Her solo music career continues apace, with a recent album titled I am...Sasha Fierce. The name has a bit of a story.

Beyoncé explains: “I get terrified before I go on stage, and the butterflies are crazy, but Sasha Fierce is my alter ego. She’s the person that takes over when it's time for me to work and when I'm on stage, this alter ego I've created kind of protects me and who I really am, underneath all the make-up.”

Behind the looks that have made her VHI’s No.1 of the 100 Hottest Hotties, Beyoncé is a caring older sister towards Solange, also a singer. She says she feels “protective” and that there’s no rivalry between them.

Away from work, Beyoncé, a noted fashionista loves shopping. And that means designer labels.

Beyoncé confesses: “I love Alexander McQueen and Jean Paul Gaultier.

“Their clothes are feminine, sexy and modern. When I go in a shoe shop it’s like being in a candy store—I am obsessed. Right now, I love anything with a high platform.”

Beyoncé doesn’t keep her millions to herself however. She’s a philanthropist and promotes black culture. Beyoncé played the title role in a biopic of noted soul singer Etta James, now 71.

Ironically, the two fell out after Beyoncé selected Etta’s trademark number for the Obama gig and the veteran performer said that Beyoncé needed her ass kicked. That was before seeing Obsessed, obviously. Just remember, you don’t mess with Beyoncé.

Obsessed is on general release from May 29.