Understudy Sapp is the temporary replacement for Christopher Fitzgerald, who departed the production Jan. 2. Fitzgerald's official replacement, Jeffrey Kuhn, begins performances in the Stephen Schwartz-Winnie Holzman musical Jan. 11.

January 11 also marks the official debuts of Shoshana Bean as Elphaba (Tony Award winner Idina Menzel plays her final performance Jan. 9) and David Ayers as Fiyero (replacing Joey McIntyre).

Robb Sapp is currently making his Broadway debut in the ensemble of Wicked. His other theatrical credits include The 25th Annual Putnam County Spelling Bee, Zanna, Don't, Johnny Guitar, Saturday Night Fever and Spring Awakening.

Based on the novel by Gregory Maguire, which turned every Oz myth inside out, Wicked explores the early life of the witches of Oz: Glinda and Elphaba. The two main characters meet at Shiz, a school where both hope to take up sorcery. Glinda is madly popular and Elphaba is, well, green. By a misunderstanding, they wind up roommates and, after an initial period of mutual loathing, begin to learn something about each other. Their life paths continue to intersect through a shared love, entry into the Emerald City and interaction with the Wizard himself. Eventually, their choices and convictions take them on widely different paths.

With a score by Stephen Schwartz and a book by Winnie Holzman, Wicked began previews on Broadway Oct. 8, 2003, with an official opening Oct. 30, 2003. The company currently includes Tony winner Menzel as Elphaba, Jennifer Laura Thompson as Glinda, George Hearn as The Wizard, Carole Shelley as Madame Morrible, Joey McIntyre as Fiyero, Michelle Federer as Nessarose and William Youmans as Doctor Dillamand. Directed by Joe Mantello, Wicked features choreography by Wayne Cilento and plays the Gershwin, 222 West 51st Street. Tickets are available by calling (212) 307-4100 or by visiting www.ticketmaster.com.