Sync or swim for Ryan and Kathryn

STEP UP 4: MIAMI HEAT

Starring: Kathryn McCormick and Ryan Guzman.

Director: Scott Speer.

Certificate: PG.

What's it about? A young aspiring dancer arrives in Miami and falls for the leader of a urban flash mob dance crew. Body popping ensues.

Verdict: Vibrant fun for teens.

R aw, unbridled energy, passionate clinches and killer moves are all essential ingredients for a decent dance movie.

Since the series began in 2006, the Step Up films have all been global box office winners, with the first transforming Channing Tatum from unknown pop-and-locking hunk into full-blown Hollywood heart-throb.

According to its stars, newcomers Kathryn McCormick and Ryan Guzman, Step Up 4: Miami Heat has raised the bar once again.

The pair, who make their big-screen debuts in the 3-D movie as the leads, say the concept of making a third sequel did not faze them.

"There's no more battling, there are flash mobs instead," says McCormick, who plays aspiring dancer Emily.

"It's all different styles. I think it's really rare that you see a dance film that doesn't have some sort of battling at some point.

"This film just represents dance in such a positive way."

McCormick, who prefers not to divulge her real age, reveals she never expected to be given the opportunity to act.

"This is something I never thought I would be doing in a million years. It's surreal, and I'm so grateful for this opportunity," she says.

"I've been dancing for a long time, about three years professionally, and if I look back four years ago, I could never have imagined myself in this position.

"For the director and producers to believe in me and give me a chance was incredible."

For Guzman, acting is a whole new world from his usual Mixed Martial Arts (MMA) fighting and modelling.

The toned 24-year-old had never acted prior to his role of rebellious street dancer Sean, and is tipped for big things, after being dubbed "the next Channing Tatum" by Speer.

"The audition process was really scary for me, especially free-styling in front of a bunch of people, but it made me that bit more motivated," he admits.

"I was practising until 1am, and then showing up early to do my thing."

"I heard I was against 300 people and they're real professionals."

"The guy who made it into the last round with me had danced for Madonna and Britney Spears, and had a long list of amazing names." He didn't have to dance for the audition process.

"They put me through the wringer. It was about a month and a half of auditioning – four acting auditions, and then six dance auditions, so it was tough.

"I don't know what they saw in me, but I'm glad they saw something."

Things didn't get easier, even after Guzman won the part by wowing the crew with his "incredible charisma".

"I have been fight training for years, but dance training was as intense as anything I've ever done in my life. It's physically, mentally and emotionally draining," he says.

"But I pushed past the fear.

"Even though they had a dance double ready to fill in for me, I said, 'No way'. This is my movie, I want to do everything."

Away from the gritty urban areas of New York and Baltimore, Step Up 4: Miami Heat, as the title suggests, has relocated to the sunny climes of Florida.

"Miami has its own live energy about it, and I think we did it justice, whether it be flash mobs on Ocean Drive in the middle of the day, or dancing on the beach. It was just really, really fun," says Guzman.

Filming in the 40C heat proved to be another challenge.

Guzman, who is seen shirtless in a number of scenes in the film, jokes: "I kept myself cool because, luckily, the wardrobe didn't like to put me in a lot of clothes while I was filming. So that helped a little bit!"

Step Up 4: Miami Heat opens in cinemas next Friday

Channing Tatum Who ever expected that back in 2006, when he starred as rough-and-ready Tyler Gage in Step Up, that six years on, Tatum would be married to his co-star Jenna Dewan and have a stellar Hollywood career, working with the likes of Steven Soderbergh?

Jessica Alba She may have made an impressive Dark Angel, but it was her moves in 2003's Honey that propelled her to mainstream fame, with later roles in Sin City, Fantastic Four and The Killer Inside Me.

Flawless The Britain's Got Talent finalists may have lost out to fellow dance troupe Diversity, but they have appeared in StreetDance 3D and StreetDance 2, and performed for the Queen.