When Celine Dion's producer David Foster first heard Josh Groban, then 17, while booking performers for the 1999 inauguration bash for California Gov. Gray Davis, he recalls, "It floored me." Viewers who saw Groban close the Winter Olympics with Charlotte Church or on 20/20 reacted instantly too, making his debut classical-pop album with Italian songs, Josh Groban, an unlikely platinum smash, selling more than a million so far. "They see him on TV, they go on the Internet, and they click to buy," says Foster. "It's been pretty amazing."

It's not like Mom (Lindy, 59, an artist) and Dad (Jack, 56, a corporate recruiter) walked around trilling arias either. "I'd come home from a [seventh-grade] show," says Groban, 21, "and go, 'Mom, check this out, Laaaa.' She would be like, 'That's great. Go to your room.'" Soon he was treading the boards—and cleaning them—in high school plays: "I was Broom Sweep No. 3 in Sweeney Todd" Last year Ally McBeal producer David E. Kelley heard Groban at an L.A. charity gig and cast him as Ally's date. "All of a sudden," says Groban, who isn't seeing anyone in real life, "I had, like, this whole part in the season finale!"

The deal for his CD soon followed. "He is not unlike the male Celine Dion," says Foster. Except maybe for what's in their CD players. "He knows the songs from Motorhead, Radiohead and Portishead," says Foster. "All the heads."