Selena Gomez looked to be in good spirits while arriving at the Vanity Fair Oscar party on Sunday.
But according to a RadarOnline source, once inside the event the 21-year-old had a little too much fun.
On Monday the site reported the 21-year-old was 'boozing it up and stumbling' out of the event. This comes just weeks after the Wizards Of Waverly Place actress left a rehab center for exhaustion.
Selena's rep did not returns calls to MailOnline.
Radar went into detail about Gomez's night of partying, pointing out she was sipping on champagne and perhaps something stronger.
The star was never photographed with a drink in her hand, however, and a source told MailOnline, 'She wasn't even there very long.'
'Selena was drinking constantly throughout the entire party when I saw her,' the eyewitness insisted to Radar.
'She was having a grand old time and towards the tail end she was stumbling in her heels and almost toppled right over!' the source added.
The beauty shared a fun photo with friend Vanessa Hudgens in an Instagram snap.
It was captioned, 'My only, official party buddy for life ;)'
'Selena and Vanessa were just having a really good time, laughing and taking pics,
' the source said.
'She wasn’t slurring too bad, but was definitely in the happy-sleepy stage.'
In January the Love You Like A Love Song singer spent two weeks in an Arizona rehab facility.
In February her rep told Radar, 'Selena voluntarily spent time at Meadows but not for substance abuse.'
The day after the party, Gomez looked just fine - as in she didn't have a hangover - as she headed to a dance studio in LA.
In addition to being accused of letting her hair down for the night, Gomez was singled out by ex-boyfriend Justin Bieber for her stunning Oscar style.
'Most elegant princess in the world,' he captioned a set of photos of Selena in a gold gown.
The Shake It Up singer did stand out on the carpet for her plunging neckline gown that was sheer toward the bottom.
Long wavy hair and black cat eyes added to the glamorous look.
The gushy note comes as a bit of a surprise after the couple reportedly had a bad falling out earlier this year.
They were last seen together in January riding Segways. The two had also posted an Instagram photo where they were in an embrace at about the same time.
Bieber did not attend the Oscars and it's believed he was in Atlanta, Georgia on Sunday evening. The star has been residing in that city for the past several weeks, and even spent his 20th birthday there on Saturday.
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