OK, this is going way back, but it was an unforgettable night. The musical was Scarlett, the Harold Rome adaptation of Gone With the Wind starring Lesley Ann Warren. It was 1973, and I saw the show with Lesley first. The following week I was back at the Dorthy Chandler Pavillion in Los Angeles, this time in the rehearsal rooms for an audition. A friend of mine was stage manager on Scarlett, saw me in the hall and pulled me aside and told me they were in chaos. Warren was sick (the pressure on her must have been tremendous: everything on her shoulders, bad reviews, constant fixes going in, and I think she was just separating from Jon Peters at that time).
Anyway, her understudy started rehearsal to go on for her, but she got sick as well and couldn't do it. So they were currently rehearsing Udana Power, who played Melanie, as Scarlett, and putting Udana's understudy in as well. Needless to say, I wanted a ticket to see that.
I can definitely say that Ms. Power's performance was one of the most heroic I have ever seen. What had been dull a week before was now riveting just watching the cast and crew try not to kill each other with mansions and battlefields sailing across the stage. "As God is my witness" they all made it through and got what was maybe the only standing ovation of the LA run.
The show went to San Francisco after that, then Phoenix and I think some other cities, but they never brought it in to Broadway. (Good call, that.)