The actress, who is playing Judy Garland in the upcoming biopic Judy, recorded a duet with Smith for the film’s soundtrack. The pair joins forces for a cover of Garland’s song “Get Happy,” while Zellweger also sings “Have Yourself a Merry Little Christmas” with Rufus Wainwright in another track on the album.
“When I was 17 years old I did a project on Judy Garland for my Film Studies A-Level,” Smith — who previously won an Oscar for his song featured in the 2015 James Bond movie Spectre — said of the partnership. “I was immediately immersed into the magic of Judy and her incredibly brave and triumphant story.”
“She has remained as one of the icons of my life,” the singer, 27, continued. “She was one of the bravest humans out there and her vulnerability and honesty in her art still gives me goosebumps like it did the first time. It was truly an honor to sing with Renée … it is a career highlight for me to be singing with her and, in some small way, with Judy.”
The soundtrack’s lead single, Zellweger’s cover of “Over the Rainbow,” will be released on Friday, while the full album will drop next month.
The film chronicles Garland’s journey to London in the winter of 1968 for a series of sold-out concerts she performed despite her exhaustion and deteriorating health. The Wizard of Oz star died in London in 1969 of an accidental barbiturate overdose just months after the tour ended. She was 47.
Zellweger dedicated a great deal of time to learning how to fully encapsulate the star by taking music lessons, studying choreography and reading up on the actress and singer.
To capture her look, the Bridget Jones actress spent two hours a day in a makeup chair getting prosthetics, contact lenses and wigs applied.
“It was such a joy learning about the magnificence of this person,” Zellweger previously told PEOPLE. “I always admired her. She was so quick and so funny. She could hit the ball back with the best of them.”
In addition to Zellweger in the title role, the film stars Finn Wittrock as Garland’s fifth husband Mickey Deans, Rufus Sewell as her third husband Sid Luft and Michael Gambon as her manager Bernard Delfont. Bella Ramsey plays Garland’s daughter Lorna Luft while Gemma-Leah Devereux plays her daughter Liza Minnelli.
Judy hits theaters Sept. 27, and the soundtrack is set to be released the same day.