'Judy': Renee Zellweger transforms into Judy Garland in trailer for film biopic

The actress takes on Garland's 'Somewhere Over the Rainbow' in the new teaser

Renee Zellweger as Judy Garland in 'Judy'. YouTube / Roadside Attractions

Cinemagoers should prepare to discover somewhere over the rainbow again this year, as Renee Zellweger steps into the shoes of singer and actress Judy Garland.

Bridget Jones star Zellweger will portray The Wizard of Oz legend in a new film biopic, the first trailer for which was released on Friday.

Judy, which is due to hit screens in September, charts Garland's final year before her death of an accidental overdose in 1969, aged just 47.

The film follows the Grammy, Tony and Golden Globe-winning star as she embarks on a series of comeback concerts in London, amid a time when she was battling financial difficulties and substance abuse.

Judy is helmed by British theatre director Rupert Goold, and based on Peter Quilter's play End of the Rainbow, which first premiered in Australia in 2005.

In the just-released teaser, Zellweger – who proved her musical chops as Roxie Hart in 2002's big-screen adaption of Chicago – provides a moving rendition of Somewhere Over the Rainbow, as she embodies Garland in a short, dark wig.

“I made it clear to Renee that I wasn’t looking for an impersonation of Judy Garland’s inimitable voice, but what I wanted was for Renee to make the songs her own, and this she did to thrilling effect,” Goold said on Friday in a statement.

“I had always wanted to make a film that explores great performance and its cost. The most fertile ground for such exploration seemed to be at the end of a lifetime of performance.”

The film forms part of 50-year-old Zellweger's own comeback - the star took a six-year hiatus from the big screen, returning with 2016's Bridget Jones's Baby.

The Texan actress this month opened up to People magazine about the "magical" experience of becoming Garland, revealing that she took music and dancing lessons in preparation.

“It was such a joy learning about the magnificence of this person,” said Zellweger. “I always admired her. She was so quick and so funny. She could hit the ball back with the best of them.”

Judy also stars Games of Thrones' Bella Ramsey as Garland's daughter, Lorna Luft, Rufus Sewell as Lorna's father, Sidney, and Finn Wittrock as Mickey Deans, Garland's fifth and final husband.

The star's eldest child, actress and singer Liza Minnelli, has previously stated that she does not approve of the biopic.

“I have never met nor spoken to Renee Zellweger ... I don’t know how these stories get started, but I do not approve nor sanction the upcoming film about Judy Garland in any way," she posted on Facebook last year.