It’s been three years since Renée Zellweger last graced the big screen in Bridget Jones’ Baby, and she couldn’t have chosen a better project for her big return than Judy, the unconventional Judy Garland biopic that follows the entertainer during her late-in-life London residency. As Judy, Zellweger is astonishing, delivering a performance that captures Garland’s star power and struggles, her dynamism and distress, but is never an impersonation; pundits are saying Zellweger will be hard to beat come awards season, and it’s hard to argue with them. Ahead of the movie’s theatrical release, Zellweger sat down with Rotten Tomatoes to reveal how she became Judy for the Certified Fresh film, from her deep research to the intense vocal training that would allow her voice to soar over that rainbow.