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Rihanna is known to be fearless and utterly confident on stage and in the recording booth, but on the big-budget Battleship set, she had to contend with a few butterflies.

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Appearing at the Battleship premiere in Tokyo, which was held on a real-life U.S. battleship, Rihanna explained how she was thrown into the mix while shooting.

"It was my first film, so obviously you could just imagine how nervous I was," said Rihanna, who rocked her new jet-black coif. "The first day in, [director Peter Berg] didn't really give me a chance to think about it before I was already shooting a scene ... In that way it was incredible."

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Battleship, which is based on the classic naval battle board game by Hasbro, also stars Oscar-nominated actor Liam Neeson, Just Go with It star Brooklyn Decker and Friday Night Lights hunk Taylor Kitsch.

The heart-pounding action flick shoots into theaters May 18.