Sunday, March 1 marks Justin Bieber's 21st birthday. And while he has yet to post any photos from his birthday celebration that began the night before, the pop star's model friends, Hailey Baldwin and Yovanna Ventura, posted Instagram photos of themselves cozying up to him, Entertainment Tonight reports.

Baldwin posted a photo of her arms wrapped around a shirtless Bieber, while Ventura posted a photo of a shirtless Bieber grabbing her thigh.

Check out the photos below.

 21

A photo posted by Hailey Baldwin (@haileybaldwin) on Feb 28, 2015 at 8:10pm PST

Happy birthday!!  A photo posted by Yovanna Ventura (@yoventura) on Feb 28, 2015 at 8:10pm PST

The Daily Mail reports that Bieber started his birthday celebration late Saturday night with a house party that involved lots of champagne drinking and Corona lights.

According to the Daily Mail sources, Bieber attended his house party with basketball shorts and no shirt. He was allegedly drinking the entire night and his party guests filmed him dancing to 50 Cent's "In Da Club."

And while it is clear that Bieber was enjoying himself, the singer has been trying to change his image.

Following his recent interview on the "Ellen" show, Bieber posted a Facebook video apologizing to his fans and critics for his bad boy behavior in the past.

"I didn't want to come off arrogant or conceited, or basically how I've been acting the past year and a half. And I'm not who I was pretending to be," he said in the dimly lit video. "I say pretending [because] often we pretend to be something we're not as a cover up of what we're truly feeling inside."

Bieber then went on to name "growing up" as the reason why he's acted so inappropriately over the years.

"Just being young and growing up in this business is hard. Just growing up in general is hard. I want people to know how much I care about people. I'm not that person to say 'I don't give a f*ck.' I'm not that kid. I'm a person who genuinely cares," he said.

Check out Bieber's Facebook video below.

Post by Justin Bieber.