07/22/2013 09:46 EDT

Selena Gomez Parties Without Justin Bieber At Pre-Birthday Bash (VIDEO, PHOTO)

Selena Gomez got an early start to celebrating her birthday when she was snapped partying up a storm sans maybe boyfriend Justin Bieber over the weekend.

The "Come and Get It" singer, who turns 21 on Monday, sported devil horns and matching red lips at "Rock of Ages" star Julianne Hough's birthday bash with friend and actress Lily Collins.

The Biebs might have been invited to the party but the Canadian pop star was performing in Boston and is due in Canada for three shows this week.

Luckily for Bieber, the "Spring Breakers" stunner wasn't photographed surrounded by a bunch of studs but we're sure she made guys drool in her cute sheer flapper dress.

So what is the raven-haired cutie doing to celebrate being legal? Gomez told MTV back in May that she was planning a huge bash. "I'm going to have a huge party, so I'm excited," Gomez said. "I'll have all of my friends. I don't really celebrate my birthday; I go out to dinner with my friends."

Let's hope the rigidly-controlled pop star doesn't get too wild on her birthday!

Selena looks really different:

Photo gallery Selena Gomez Style Evolution See Gallery