Oh, it is on.
During an appearance on Bravo's "Watch What Happens Live" Tuesday night, Broadway legend Patti LuPone dismissed Madonna's entire film career, saying she's a "movie killer."
The two have a major role in common: LuPone played Eva Perón in the original Broadway production of "Evita," while Madonna played her in the 1996 film version.
"She's a wonderful performer for what she does, but she's not an actress," LuPone said. "She's dead behind the eyes. She cannot act her way out of a paper bag. She should not be in film or on stage."
LuPone, who recently received a Tony nomination for her role in the show "War Paint," was asked by a caller whether she and Madonna had ever discussed their respective performances in "Evita." The actress, 68, said no, but added that she did run into Madonna once when the singer was appearing on Broadway in the play "Speed-the-Plow."
"I did meet her after her opening night party," LuPone told host Andy Cohen. "And the only thing that Madonna has ever said to me was, 'I'm taller than you.'"
When Cohen followed up by asking LuPone what she thought of Madonna's portrayal of Eva Peron in the 1996 movie "Evita," Lupone didn't hold back. Noting that she saw just one song from the movie -- "Buenos Aires" -- on MTV back in the day, the actress said, "I thought it was a piece of s---."
ABC News has reached out to Madonna's reps to see if the Queen of Pop has a reaction to LuPone's comments.