Andrew Samonsky, currently playing Lieutenant Joe Cable in South Pacific, has a confession: he hasn't always liked singing Cable's showstopper "Younger Than Springtime." This attitude had nothing to with the song itself, which he thinks beautiful, but with his voice. "I started out as a baritone, even a bass-baritone," he says, "so singing something so associated with tenors always made me a little afraid. In college, my voice teacher would use 'Younger than Springtime' to stretch out my voice. But the song was too hard, too high."

Samonsky, who spoke to me from Cable's dressing room between Wednesday shows this week, has had to confront a few fears, or at least serious jitters, since South Pacific began its run. Signed up to play Lt. Eustis Carmichael and to understudy the part of Cable, Samonsky got a call one Saturday morning during previews in March. "[Stage manager] Mike Brunner told me that Matthew Morrison was indisposed." (Morrison generally plays Cable but is on a five-week break to film a new TV comedy called "Glee.") "And so I was going to have to go on as Cable for the matinee. I went to the gym, got to the theater at 11 am, and walked through the blocking. Next thing I know, I'm singing opposite Kelli O'Hara. It was surreal. I'm sure I had fears, but my body went into hyper-focused mode and somehow I got through it."

Samonsky suspects that his professional experience -- he'd been working for five years, regionally and on tour -- helped him during that first Cable experience, just as he thinks that his undergraduate operatic training at Cal State-Northridge (he later studied acting at UC-Irvine) aids him with South Pacific's eight shows a week. "Studying opera teaches stamina," he says.

Growing up in Ventura, California, Samonsky admits he wasn't a natural fit for working in opera, which he eventually found "too stuffy, too limiting." But with his sports-inclined father and with both his parents fond of musicals, he says his transition to the world of South Pacific "feels very appropriate." He continues: "There's so much masculine energy in this show, and I've come to understand why sailors' bonds with each other were so intense."

As are the friendships among the actors who play those military men. "Sometimes I think we have almost too much fun in the ensemble," Samonsky says. "When I hear 'There Is Nothing Like a Dame' backstage now, and I'm not in it, I start to miss those guys. But then I remember how grateful I am to be playing Cable, and to sing his fantastic songs."

Even "Younger Than Springtime"? "Yes," Samonsky answers. "After all the struggle I had with it years ago, I can finally say I'm not afraid of 'Springtime' anymore."

BRENDAN LEMON is the American theater critic for the Financial Timesand the editor of lemonwade.com