Mariah Carey and Olivia Newton-John join forces for Instagram duet

By Sarah Kelsey

Mariah Carey met Olivia Newton-John on Monday night, and the mutual fans quickly became hopelessly devoted to each other. The vocally talented duo caught their Monday night (May 25) meet-and-greet on camera, later posting the short video to Instagram.

In the clip, the pair can be seen posing poolside in matching black outfits - Mariah in a black-and-gold frock with a plunging neckline and Olivia showing a bit less skin in a black top and fringed, gold necklace.

Reunited in Vegas! Love you Olivia Newton John!! #HopelesslyDevotedToYou @therealonj

A video posted by Mariah Carey (@mariahcarey) on

The spot begins with a starstruck Mariah proclaiming, " This is Olivia Newton-John, come on!" The 45-year-old songstress goes on to embrace the Australian star, who quickly reciprocates the love by saying, "This is Mariah Carey, are you kidding me?" The 66-year-old singer then begins to belt out one of the tunes that made her famous, Grease's "Hopelessly Devoted to You." Carey quickly joins in.

Read more: Mariah Carey announces Las Vegas residency, will fill in for Celine Dion

This isn't the first time the world-famous pop stars have shared a moment of song. Back in 1998 they performed the same Grease hit in Melbourne while Mariah was touring Australia on her Butterfly World Tour.

Olivia presented Mariah with an award at the 2000 AMAs. Photo: © Getty Images

It’s no coincidence that the two singers bumped into each other in Vegas, either. Olivia is currently in the Nevada-based city for a summer stint at the Flamingo, where she can be seen performing some of her biggest hits, while Mariah is filling in for Celine Dion at Caesar’s Palace. The Canadian singer has been taking time off to take care for her ailing husband, René Angelil, but made a dazzling return to the public at the 2015 Billboard Music Awards and will return to Caesar's Palace on August 27.

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