NEW YORK — Elvis Costello has become sort of an expert in collaborations, having worked with everyone from Burt Bacharach to the Brodsky Quartet over the past 10 years.

But his pairing with mezzo-soprano Anne Sofie von Otter on the recent album "For the Stars" wasn't his idea.

"Actually, it was Anne Sofie's husband who said it first, like, 'Oh, you should work together sometime' — just like that, not very seriously," the 47-year-old British musician said. "I was really taken aback. It had never occurred to me. I just thought her kind of singing was completely beyond my comprehension."

Costello became a fan after his wife encouraged him to attend one of von Otter's concerts. After her performance, the couple sent flowers to show their admiration.

"(Then) she invited us to like an after-concert supper, and we were introduced, and we talked," he said. "And discovered we had more in common than you might imagine."

"For the Stars" features relatively obscure pop songs performed by von Otter. Costello, who produced and arranged the material, doesn't sing.

However, Costello and von Otter performed together this summer in a concert that was filmed by director Ted Demme for a documentary.

1. After seeing von Otter perform, did you try using your celebrity to go backstage?

Costello: I don't go backstage to see people I don't know. But we sort of sent the flowers with a card or something and eventually, I think after a few days . . . we were introduced.

2. How did you pick the songs for the disc?

Costello: We looked at a whole range of material. . . . I think it's very natural for her to want to explore every possibility, because her own range in classical music is enormous.. She goes from Verdi to Stravinsky and even contemporary compositions. . . . We found a lot of really great songs that we wouldn't have done if we hadn't spent 3 1/2 years looking for them.

3. Why didn't you consider adapting the disc more to von Otter's operatic style?

Costello: She obviously could do that perfectly well without my involvement. I appreciate a lot of this music, but I wouldn't presume to be an authority on it.

4. Classical crossover records are often skewered by the critics. What's your opinion of some of today's pop-classical collaborations?

Von Otter: I think they're trying to do their best and I think they really like what they're doing, so I'm not really one to judge, but you can hear a mile away that it's an opera singer doing this. . . . I don't have that great hate or dislike for other crossover recordings.

Costello: It might sometimes be very hard on the ears, if you like those songs, and you hear somebody who is being very poorly advised in the way to approach it. . . . (But) people get too hot under the collar about it, really. . . . It's only a bit of fun.

5: Can you see yourself doing a collaboration with 'N Sync or Britney Spears?

Costello: You never know what might happen. It's not like I'm looking for another collaboration, as if that is my reason to carry on. . . . I do feel it is my turn now to sing my own songs. So I don't have a secret short list of people I long to work with. I don't anticipate (saying), 'Has anyone got Christina Aguilera's phone number?' It doesn't work like that.