Pop diva Rihanna is totally unrecognizable in her first acting role as a soldier taking on some scary aliens in the upcoming 'Battleship.' Gone are the wild wigs and barely-there outfits; instead, she's in a uniform and wielding some badass looking artillery.

Although she's in pretty amazing shape (as those skimpy stage costumes clearly show), she had to undergo intensive military training for the role.

"We worked with real military people ... people in the Navy, people who have fought in Iraq before," Rihanna explained. "This one man, Donald, he pretty much drilled me, yelled at me, cursed me, made me do push-ups... I really wanted to say, "F**k you" right back, but then he probably would have thrown me through the window! I was so scared. I just stood there and looked at him like, 'I swear I'm going to get it right, I swear, I swear, I swear I'll be good.'" img border="1" hspace="4" id="vimage_4362370" src="http://www.blogcdn.com/blog.moviefone.com/media/2011/08/battheship-boat.jpg" vspace="4" />

She said the training helped her "get into the mentality" of being a naval officer. "It's not a walk in the park."

As for director Peter Berg, Rihanna said, "He's crazy. He really is, and so spontaneous, so nothing is memorized, it's a real reaction every time. I couldn't ask for a better director to work with on my first film. Who warns you that you have to jump into the middle of the ocean and pretend that you're drowning? Who does that? Him? Never."

The singer said that acting is completely different than shooting a video. "It's night and day. I don't even want to think about being on stage right now. Being on stage, is a ... world that I'm a little more comfortable with. This is a whole different perspective, I mean it seems the same, it's not even the same as shooting a video. It really isn't."

And, for the record, Rihanna's never played the board game that inspired the movie. "In Barbados that doesn't even exist," she said, although the production did give her a copy of the game in her trailer.

Does she get to utter the famous "You sunk my battleship!" phrase? "No, that's not my line. Yeah, no one sinks my battleship."

'Battleship' stars Taylor Kitsch , Alexander Skarsgård and Liam Neeson. It opens May 18, 2012.

[via UGO]