Hugh Grant jokes that he was prepared to be intimidated by his "Florence Foster Jenkins" screen partner Meryl Streep, but was surprised to see what a tremendous comic force their co-star Simon Helberg turned out to be.

"I became gradually aware that I should have been frightened of HIM," Grant said of Helberg at a New York press conference Tuesday.

"I knew you were in the sitcom, but I didn't realize how gigantic it was," Grant addressed the younger actor as he referenced Helberg's hit show "The Big Bang Theory."

"And that, really, you're probably the richest man I've ever met."

"Be nice to me," Helberg teased.

Set in 1940s New York and based on a true story, Florence Foster Jenkins is about a society dame whose awful singing voice and determination to perform at Carnegie Hall made her a legend.

Grant plays the husband who tries to protect her from those who would ridicule her, while Helberg portrays the piano player who accompanies her during her singing lessons, as well as for an epic, sold-out show at the storied, Manhattan venue.

The film is to open in U.S. theaters Friday.