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She's back -- in more ways than one! It turns out Chrissy Teigen, Nina Agdal and Lily Aldridge aren't the only models gracing the cover of the 50th Anniversary issue of Sports Illustrated Swimsuit edition. For her third year in a row, Kate Upton is featured on the coveted magazine -- but this time on the back.

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Sports Illustrated revealed that the bonus backside cover features the 21-year-old American model. For her shot, Upton shows massive cleavage in a skimpy pink bikini while posing on the beach in the Cook Islands. The young model previously showed off her famous curves on the Sports Illustrated Swimsuit issue cover in 2012 and 2013.

Upton's photo shoot within the issue is also getting a lot of attention. She was photographed in a zero-gravity chamber wearing a sexy gold bikini from the Target Limited Edition Collection.

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After the magazine revealed last week that Teigen, Agdal and Aldridge scored the front cover this year, Upton congratulated the girls on Twitter. "OMG! So happy for @LilyAldridge @chrissteigen and @NinaAgdal!!" she wrote on Feb. 14. "What a gorgeous cover!! Loving the booty for vday."

For their photo shoot, the three models posed topless in bikini bottoms with their backs to the camera.

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