08/12/2013 10:00 EDT

Teen Choice Awards 2013: Selena Gomez Looks Serious In Double-Slit Dress (VIDEO, PHOTOS)

Selena Gomez rocked one of the hottest looks at the 2013 Teen Choice Awards but you wouldn't guess it judging by the young star's face.

Justin Bieber's maybe-girlfriend hit up the red carpet on Sunday night in a super sexy green Cushnie et Ochs dress with a double thigh-high slit and shoulder cut-outs.

But instead of flashing her pearly whites, the 21-year-old seemed to be in a sombre mood, barely mustering a smile for the cameras. Why so glum, Selena?

It might have something to do with the recently leaked pics of Bieber in the nude! TMZ posted photos of the Biebz strumming a guitar buck naked while at his grandma's house in 2012. And yes, Grandma Bieber was the only lady in the photos.

Not that Selena would be jealous. The "Come and Get It" singer was recently spotted partying solo at friend Julianne Hough's birthday party in a cute flapper dress.

Who needs guys when you have best friends?

Photo gallery 2013 Teen Choice Awards See Gallery