With their roles in young adult novels adapted into film, a Lily Collins vs. Shailene Woodley battle is brewing. Lately, the "Mortal Instruments" star and the "Divergent" actress can't seem to get enough of bare midriff outfits.

Lily Collins and Shailene Woodley promote their movies.

Lily Collins and Jamie Campbell Bower joined their cast mates on a tour of U.S. malls to meet with "Mortal Instruments" fans. Lily Collins bared her midriff in a printed Christian Siriano ensemble. Lily loves print and shorts but she has never worn something as daring as her outfit at the Chicago Ridge Mall on July 30. Lily paired a black, cropped top with a geometric print jacket and pleated shorts. This was a fun, youthful look for the 24-year-old actress.

Another bare midriff came courtesy of the lead actress in the upcoming "The Fault in Our Stars." Shailene Woodley and Theo James have a bit more time before "Divergent" opens in theatres. Until then, Shailene is busy with "Spectacular Now." The film premiered in Los Angeles on July 30 and the 21-year-old showed her tasteful, all-black take on the trend, with some help from Proenza Schouler. Shailene looked sophisticated in a sleeveless, high-neck top and draped skirt. With her height, Shailene managed to pull off her skirt's tricky length. Black Proenza Schouler sandals and a unique, dream catcher style H.O.W.L. necklace completed Shailene's red carpet look.

The Lily Collins vs. Shailene Woodley bare midriff outfit battle did not begin, or end there. It seems like these two young actresses are trying to prove that belly baring isn't just for the likes of Lady Gaga, Miley Cyrus, and Rihanna, who tend to use bras as shirts.

Lily Collins and Shailene Woodley bare their midriffs.

Lily Collins, Jamie Campbell Bower, Kevin Zegers, and other "Mortal Instruments: City of Bones" cast members attended Comic Con in San Diego. Once again, it was shorts and printed fabric for Lily. She rocked a Paper London cropped top and printed panel shorts, with Brian Atwood pumps.

Another "Spectacular Now" screening brought Shailene Woodley and Miles Teller together. The pair headed to the Hamptons in appropriate attire. Shailene wore an ivory Apiece Apart cropped top and skirt, with nude Jimmy Choo sandals. With barely-there makeup and beachy waves, Shailene aced the effortless look.

So far, it's two for two for both Lily Collins and Shailene Woodley, but click on the photos and decide who wins the bare midriff outfit battle.

For more on Shailene and Lily's style, read:

Shailene Woodley: 'Divergent' Style at Comic Con [PHOTOS]

Lily Collins: Steal the Mortal Instruments Star's Style [PHOTOS]

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