Lady Gaga's performance in Joker: Folie à Deux opposite Joaquin Phoenix shocks the sequel's casting director - who admits she didn't cast Gaga: 'She's going to blow your mind'

Lady Gaga is set to expand her burgeoning film career even further when she stars opposite Joaquin Phoenix in the sequel Joker: Folie à Deux.

And now the casting director for the highly anticipated sequel is sharing her thoughts on Gaga's buzzy performance — and she admitted that she wasn't the one responsible for casting the 38-year-old pop icon in the superhero-adjacent thriller.

Francine Maisler, who served as the casting director on the Joker sequel, said Gaga — who shot down pregnancy rumors last month — was 'so good' in Folie à Deux during a talk at the Karlovy Vary International Film Festival in the Czech Republic earlier this week, according to Deadline.

'She’s going to blow your mind,' Maisler gushed to the audience, before admitting that she couldn't take credit for her presence in the film.

'It wasn’t my idea. That was Todd Phillips, before me,' she said, referencing the returning director, producer and co-screenwriter.

Joker: Folie à Deux's casting director Francie Maisler raved about Lady Gaga's performance in the film during a talk at the Karlovy Vary International Film Festival in the Czech Republic earlier this week, according to Deadline; Gaga pictured May 23 in LA

Joker: Folie à Deux's casting director Francie Maisler raved about Lady Gaga's performance in the film during a talk at the Karlovy Vary International Film Festival in the Czech Republic earlier this week, according to Deadline; Gaga pictured May 23 in LA

Gaga stars as Harleen Quinzel, aka Harley Quinn, who falls in love with Arthur Fleck (Joaquin Phoenix) ¿ better known as the Joker ¿ when they're incarcerated together in a mental hospital; pictured in April 2023 while filming Joker: Folie à Deux in NYC

Gaga stars as Harleen Quinzel, aka Harley Quinn, who falls in love with Arthur Fleck (Joaquin Phoenix) — better known as the Joker — when they're incarcerated together in a mental hospital; pictured in April 2023 while filming Joker: Folie à Deux in NYC

Part of what blew Maisler away was seeing Gaga stretch herself beyond her obvious strengths.

'I will tell you, [Gaga's] really surprising — and really good. I saw it and I was really surprised,' she said. 'I mean, we all knew what she could do in A Star Is Born, but I thought, "Oh, well, that’s kind of in her wheelhouse." Something she could do and just be real. 

'But this… Man, she’s good,' Maisler enthused. 'Joaquin blows your mind, but that she could keep up with him, and be real — and not just wiped off the screen by what that role is and what the performance is — shows she’s good.' 

Although Maisel didn't think the Joker sequel was outside of Gaga's wheelhouse on its face, the film will likely play to her strengths, as it has been described as musical.

It takes place following the events of the first film, when Arthur Fleck (Phoenix) has been incarcerated at the Arkham State Hospital.

It's there that he meets a fellow mental patient, Harleen Quinzel (Gaga), and the two quickly fall in love while bonding over their shared musical delusions. 

As their infatuation for each other deepens, Arthur's deranged followers — who witnessed him murder the late-night television host Murray Franklin (Robert De Niro) in the first film — take to the streets in hopes of allowing him to subject Gotham to even more destruction.

The film takes place in the same fictional city as the Batman films and comics, but it's unclear if the Caped Crusader exists in this version of the universe.

Maisler gushed that Gaga's performance would 'blow your mind,' and she said the pop star showed off her range even more than in A Star Is Born

Maisler gushed that Gaga's performance would 'blow your mind,' and she said the pop star showed off her range even more than in A Star Is Born

Maisler also admitted that she wasn't responsible for casting Gaga, as director Todd Phillips already wanted her for the part; Gaga pictured May 23 in LA

Maisler also admitted that she wasn't responsible for casting Gaga, as director Todd Phillips already wanted her for the part; Gaga pictured May 23 in LA

Phillips has said he was inspired by the design and stories of classic 1970s and '80s crime films, especially Martin Scorsese's masterpieces Taxi Driver (1976) and The King Of Comedy (1982), both of which starred De Niro.

The first Joker film — which became the first theatrical Batman film to earn an R rating — took a far darker and less cartoonish approach to the title character than most previous depictions of the villain.

The film was relatively well-reviewed by critics, and it became a massive financial success, grossing $1.079 billion against a relatively modest budget of $55 million, according to Box Office Mojo.

Joker: Folie à Deux will be released in theaters on October 4 of this year.