A representative for the production told Playbill.com that Gallagher had been battling a cold for the past week and that it developed into a sinus infection.
His understudy, actor James Moye, will perform the role of Oscar Jaffe the evening of Feb. 24 and for both performances on Feb. 25. Gallagher is expected to return to the production Feb. 26.
The musical, which also stars Tony Award winner Kristin Chenoweth, began performances Feb. 13 at the American Airlines Theatre.
When Gallagher first fell ill Saturday evening, his understudy had not had sufficient rehearsal time on set, prompting Roundabout to make a last-minute call at 8:05 PM to cancel the performance after audiences were already in their seats. Chenoweth and the show's director, Scott Ellis, took to the stage to inform theatregoers of the news. Read about it here.
On the Twentieth Century will officially open March 12 for a limited 20-week engagement through July 5 at the American Airlines Theatre. The musical — featuring music by Cy Coleman and book and lyrics by Betty Comden and Adolph Green — premiered on Broadway in 1978 under the direction of Harold Prince and won Tony Awards for Best Original Score and Best Book of a Musical.
Here's how Roundabout bills the classic: "It's nonstop laughs aboard the Twentieth Century, a luxury coach travelling from Chicago to New York City. Luck, love and mischief collide when the bankrupt theater producer Oscar Jaffe (Gallagher) embarks on a madcap mission to cajole glamorous Hollywood starlet Lily Garland (Chenoweth) into playing the lead in his new, non-existent epic drama. But is the train ride long enough to reignite the spark between these former lovers, create a play from scratch, and find the money to get it all the way to Broadway?"
The American Airlines Theatre on Broadway is located at 227 West 42nd Street. For tickets, call (212) 719-1300 or visit RoundaboutTheatre.org.