Jessica Biel is a knockout in more ways than one.

At the August 13 premiere of her new movie, Total Recall, in Berlin, Germany, the 30-year-old actress turned heads in a fully-embellished, backless black Elie Saab dress. Wearing Ferragamo shoes, Biel finished her look with Lorraine Schwartz jewels and a Fendi bag.

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To prep for her role in the Total Recall reboot (costarring Colin Farrell, 36, and Kate Beckinsale, 39), Biel says she "did a mix of martial arts, boxing, weight training and lots of yoga. I also cut out wine, cheese and pasta. All the yummy stuff."

Playing a combative rebel fighter also gave Biel a huge confidence boost. "You sort of have an unrealistic view of your abilities," she admits. "I'm like, 'Oh, I could take that guy! For sure!'"

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Biel, who is in the midst of planning her wedding to Justin Timberlake, 31, held her own against Beckinsale, though. "It was two warrior women, just beating the sh-t out of each other," the actress says. "It was pretty fun!"

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According to Biel, Beckinsale -- known for her role in the Underwold film series -- could take her down in real life. "She's got more experience in this kicking-ass kind of movie world," Minnesota native Biel says. "And she's wiry. I would be afraid if I ran into her in a dark alleyway!"

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This article originally appeared on Jessica Biel's Backless Black Premiere Gown: Love It or Hate It?