Taron Egerton was shooting a big splashy dance number on a soundstage at Bray Studios outside London in October 2018 — belting out “Saturday Night’s Alright for Fighting” in a 1950s carnival-like setting while a teeming crowd of extras weaved and bopped around him — when a certain pop music legend arrived on the set. “There’s really nothing more intimidating than performing in front of Elton,” recalls the actor who portrays Elton John in Rocketman, Paramount’s $41 million quasi-biopic about the alcohol- and sex-fueled rise of glam rock’s greatest living superstar. “I don’t think I could have done it if he was around a lot. But I think he knew that. He’s very astute in that way.”

Elton John just stopping by that day was only one of the many nerve-racking challenges Egerton, 29, faced over the course of this production. (There was that argument with the director over putting an Elton-like gap between his front teeth. And the time he had to shave half his head to get John’s ’70s receding hairline just right.) Same for Paramount, which is banking on the musical biopic as its big tentpole this summer, despite an R rating, some early jeers from gay critics complaining about the casting of heterosexual Egerton as Elton and an impressionistic, nonlinear plotline filled with sequences of substance abuse and frank depictions of gay sex (which will likely get the film banned from China’s growing market). It’s even something of a nail-biter for John, who, like most glam rockers, isn’t entirely immune to vanity. He may not have visited the set a lot, but he watched every daily as soon as it was shot.

Still, if a Freddie Mercury biopic can gross $900 million worldwide and win Rami Malek an Oscar, just imagine what a movie about the guy with the feather boa and 50 shades of tinted eyewear could potentially do (and, unlike Malek, Egerton actually sings every note while in character). Queen was big in the 1970s, but John was even bigger over a much longer span, selling more than 300 million records. Even today, he’s still packing houses; his three-year Farewell Yellow Brick Road Tour, which runs through 2020, already has grossed $125 million just seven months in. It’s that potential built-in audience that could launch Rocketman into the stratosphere, and it’s one of the reasons Paramount is confident enough to debut the film in the spotlight of the Cannes Film Festival on May 16 and preview it in 400 theaters weeks ahead of its May 31 release. Not to mention the impact that sort of hit could have on Egerton’s budding prospects. “I’m at peace with however much money it makes,” the actor says, before quickly adding, “But I hope it does really, really well. If it made half of [Bohemian Rhapsody], it would be terrific for my career.”