The My Heart Will Go On hitmaker has been recruited for Ashes, an original song for the soundtrack to the upcoming Deadpool 2 release, and she is joined in the accompanying promo by Reynolds, dressed as his cheeky Marvel anti-hero.
The video features Celine belting out the tune at The Colosseum at Caesars Palace, where she stages her Las Vegas residency, as the mutant mercenary performs an interpretive dance - all while wearing high heels to top off his full-body red and black costume. The odd pair also shares a warm embrace towards the end of the track.
The Ashes footage, directed by Deadpool 2 filmmaker David Leitch, premiered on breakfast show Good Morning America on May3 when it was explained that Reynolds, in character as Deadpool, wrote a letter to Celine asking if she'd like to be a part of his "masterpiece".
Alerting fans to the new material on Twitter, Celine wrote, "Over the years I've received incredible songs and I've been involved in fun projects. Ashes is 1 of those songs and @deadpoolmovie is off-the-charts!"
She also encouraged fans to "take the most insane ride of your life when it opens" on May 18).
"You'll be laughing your 'ashes' off!," she added.
Meanwhile, her fellow Canadian Reynolds also posted a link to the humorous video on social media, and simply captioned it, "Showtime, Mama".
Deadpool 2: Original Motion Picture Soundtrack, which will be released on the same day as the film, also includes Welcome to the Party, a new collaboration between Diplo, French Montana, Lil Pump, and Zhavia Ward.
DJ Shadow and Run The Jewels, Skrillex, Cher, Dolly Parton, a-ha, and Peter Gabriel are among the other artists contributing to the project.