Lady Gaga is following up her role in 'Machete Kills' with another high profile film appearance. She has filmed a role in 'Sin City 2: A Dame to Kill For,' the sequel to the A-list packed 'Sin City' comic book flick.

Ma Monster must be a muse of sorts for director Robert Rodriguez, who lensed both movies.

Actor Joseph Gordon-Levitt, who appears as Johnny, confirmed Gaga's role in the film during a chat with a radio station in Boston, so it was he who let the cat out of the bag.

He revealed that she was a pro and did a great job, despite the fact that he was a little confused at first. "She came in, and I was like, 'Okay, they're having a huge pop star do a scene in the movie, I understand.' But then she came in and, like, nailed it," the actor said.

He furthered, "She had her character down, and she was like a total pro and did a great job. I was really impressed."

The film is due out next summer and also stars Jessica Alba, Rosario Dawson, Jeremy Piven, Ray Liotta and Bruce Willis. The extent of Gaga's role has not been detailed …yet.

Meanwhile, 'Machete Kill's lands in multiplexes on Oct. 11. See a trailer and the poster, both featuring Gaga.