The Hands to Myself star and her best friends had a girls' night out in Sin City, and their main event was the Canadian diva's residency gig at the Colosseum at Caesar's Palace.

Selena posted various photos and videos from their experience on Snapchat, including clips of her and her pals buying and wearing matching black T-shirts with Celine's face emblazoned on the front.

The 23-year-old also shared video footage of Celine during the concert, with one short clip even featuring Selena singing along to her hit Because You Loved Me. Another snap featured Celine in the middle of her stage, and Selena added the caption, "Queen", followed by numerous emoji hearts.

Later, Selena and Celine posed for an official picture together backstage, where Selena traded in her tour T-shirt for formal wear, as she happily posed next to one of her singing idols.

The show also marked Celine's final performance at Caesar's before embarking on a two-month hiatus. She only recently returned to Vegas on 23 February (16), after taking a break following the death of her husband and manager Rene Angelil, who lost his battle with cancer in January (16).

Celine took to Instagram on Sunday morning (13Mar16) to thank her fans for their support during the difficult time.

"Thanks to my fans and to the amazing Colosseum public, that night after night gave me the energy to go on and make a show that Rene would be proud of," she wrote.

Celine is set to resume her residency on 17 May (16).