By far her bravest decision was to do her own singing as Garland, in which she captures the essence of the great singer's style without slavishly imitating her. In the film she sings a number of Garland standards, including "The Trolley Song," "Come Rain or Come Shine," and the inevitable "Over the Rainbow." What may be her most touching interpretation is her acapella version of "Get Happy," which she sings when she visits the home of a couple of her gay fans.

She also performs the song (that can be heard on the soundtrack) with pop superstar Sam Smith, .

According to Smith, the duet came out of the blue after he had seen a cut of the film, directed by xxx. He told GayTimes he "just cried throughout the film, it was a really cathartic and beautiful experience."

Then "this opportunity came up which I didn't expect at all" when he was asked to sing a duet with Zellweger. He was sent "a few of the songs" she sang in the film to choose from. "And my natural gut instinct was to go for something sadder because it's my comfort zone," he told GayTimes.

"But when I heard 'Get Happy,' that song is such a juxtaposition to her life, it's like, 'Forget your troubles, come on, get happy', and it just feels right to me to celebrate her life and not mourn it, musically.

"That's what I wanted to do in that moment with you, was to celebrate her in a happy way."

Zellweger concurred. "I'm excited about it because when I hear it, it really makes me joyful, I wanna turn it up... it's a celebration, isn't it?" she told GayTimes.

You can watch the interview on the GayTimes website.

Listen to the duet here: