Diggs steps in for Norbert Leo Butz, who is on a medical leave of absence until Jan. 20. Mr. Butz's understudy, Kristoffer Cusick, is currently playing the role. Diggs will stay with the show until Jan. 18.

Butz was last in the show Nov. 23. Although there has been improvement in his condition, the actor is not yet ready to return to the show.

Generating stage chemistry should not be difficult for Diggs and Menzel; in real life, they are husband and wife.

Wicked, which officially opened Oct. 30, stars Menzel as Elphaba, the Wicked Witch of the West and Tony Award winner Kristin Chenoweth as Glinda. The cast also includes Tony and Academy Award winner Joel Grey as The Wizard, Carole Shelley as Madame Morrible, Michelle Federer as Nessarose, Christopher Fitzgerald as Boq and William Youmans as Doctor Dillamand.

With a book by Winnie Holzman and direction by Joe Mantello — a 2003 Tony Award winner for last season’s Take Me Out — Wicked features choreography by Wayne Cilento. Tickets are available by calling (212) 307-4100 or by visiting www.ticketmaster.com.