devil horns

Selena Gomez celebrated her 21st birthday two days early yesterday while partying with girlfriend Lily Collins.

The young actresses danced the night away at Hollywood's Roosevelt Hotel on Saturday. The hotel even brought out a cheetah print cake decorated with photos of the starlet.

Selena's beau Justin Bieber didn't attend the party because he was performing a concert in Boston. The pop star also has three shows in Canada starting Tuesday -- the day after Selena's birthday -- so it's unclear whether he will celebrate with his love tomorrow.

It was a night of birthday bashes for the gal pals, as they attended Julianne Hough's 1920s-themed 25th birthday party earlier that night. Selena and Lily were dressed accordingly in black flapper dresses. The singer also donned devil horns with her getup.

She accessorized her black mini dress with a feather boa, while Lily wore a turban. Both girls looked stunning with bold red lips.