Douglas Sills has withdrawn from the upcoming Broadway musical Spamalot, according to a production spokesperson. The role of Sir Galahad will now be played by Christopher Sieber.

Sieber, currently seen in the New York City Opera production of Cinderella, is a Broadway vet, having appeared in Beauty and the Beast, Triumph of Love, Into the Woods, Thoroughly Modern Millie and Chicago. He also toured the U.S. in The Music of Andrew Lloyd Webber and Meet Me in St. Louis. His other theatrical credits include The Boys in the Band, A Christmas Carol, Paper Moon and >Pal Joey. He was also recently seen starring on the small screen in the ABC comedy It's All Relative.

Spamalot, which is being billed as "lovingly ripped-off" from the film Monty Python and the Holy Grail, features a book by Eric Idle (based on the screenplay he co-wrote with fellow Monty Python creators Graham Chapman, John Cleese, Terry Gilliam, Terry Jones and Michael Palin) and music and lyrics by Idle and John Du Prez. The stage show includes three songs from the 1975 Monty Python and the Holy Grail film.

Headlined by David Hyde Pierce, Tim Curry and Hank Azaria, Spamalot also stars Michael McGrath, Steve Rosen and Sara Ramirez. The ensemble will include Christian Borle, Brad Bradley, Thomas Cannizzaro, Kevin Covert, Jennifer Frankel, Lisa Gajda, Jenny Hill, Emily Hsu, Abbey O'Brien, Daniel Pearce, Ariel Reid, Pamela Remler, Greg Reuter, Brian Shepard, Rick Spaans and Scott Taylor.

Directed by Mike Nichols and choreographed by Casey Nicholaw, Spamalot will begin previews at Chicago's Shubert Theatre on December 21. The musical starts New York performances at Broadway's Shubert Theatre on February 14 in preparation for a March 17 opening.