"So, based on info I got today, I'm gonna confirm Alec Baldwin as Dennis in Rock Of Ages. Hollah," Shankman wrote.

The '30 Rock' star will play the part of Dennis Dupree, an ex-rocker who runs the Rock of Ages nightclub in order to hold onto his rock star past. Other stars includes Tom Cruise, Mary J. Blige and Julianne Hough.

"Can't wait to start #rockofagesmovie. Julianne Hough, alec Baldwin, Mary j Blige, Tom cruis confirmed. I love my cast. More to come," the director tweeted.