New York ? Three years ago, when Rod Stewart decided to reinterpret pop standards with “It Had To Be You … The Great American Songbook,” it didn’t seem like a blockbuster career move.

The raspy-voiced rocker best known for hits like “Maggie May,” “Forever Young” and “Do Ya Think I’m Sexy” hadn’t had a hit in years, and now he was coming out with an album that featured music that was popular half a century ago.

Even Stewart wondered if the public would buy him as a classic pop crooner. But they did – in droves.

The CD became a surprise platinum success, and he quickly followed it up with two more, also top-sellers. This month, he releases his fourth in the series, “Thanks for The Memory … Great American Songbook IV.”

But in an interview with The Associated Press, Stewart says chances are slim the series will continue anytime soon. The 60-year-old – who plans on taking the next year off as his fiance prepares to give birth to his sixth child – is looking forward to other challenges, personal and professional.

Q: Why do you think the “Songbook” series has been so popular?

A: The only answer I can give you is it’s absolute gorgeous songs, and my voice, which is not so bad, and great marketing from (record mogul) Clive (Davis) and J Records. … hopefully this will be the most successful because it is the last one. Maybe I’ll pick it up again in two or three years.

Q: Why not continue doing more?

A: I could go on doing these albums every year and be pretty well assured of a good sell as well. (But) there’s so much more I want to do. I’d love to make a great American soul book; there are so many songs from different fields of music that I would like to do, that I’ve been jotting down for the last 20 years. I’m not sure what I’m going to do to yet but it certainly won’t be an “American Songbook No. 5.”

Q: What other styles would you like to explore that might surprise people?

A: I don’t think I’m going to surprise anybody. I’ve done every style of music I could possibly do apart from rap, and I don’t think I’m going to attempt that in my late stage (laughs). I’d like to do an acoustic album of maybe obscure Tom Waits, Bob Dylan songs.

After a surprising platinum-selling album and a series that followed, Rod Stewart is ready to call it quits and explore different musical avenues.

Q: What have you learned about your voice recording this music?

A: I’ve been delighted actually. The music obviously wasn’t unfamiliar with me because I was brought up on quite of it, being 60 now, so my parents played it … but it was always a challenge for me, because these songs are no means easy to sing compared to most rock ‘n’ roll or pop songs, which really have two or three chords or a couple of melodies. These songs are well-crafted songs, and I’m gonna serve you a quote now – “They don’t write them like that any more!”

Q: On this album you worked with Diana Ross and Elton John, among others. Did you record in the studio together?

A: No one really does that any more. It’s due to time schedules really. And to be honest with you, it’s a lot easier when you haven’t got the other artiste. It’s a lot easier, for me anyway … When I put on the headphones, I can close my eyes and pretend Elton’s there. Because no matter how big you are, you’re a little nervous and hesitant before you go in and sing with someone like Diana Ross – she may have been a little nervous with me. Elton and I wouldn’t have been nervous. But it would have been totally impossible for us to work in the same place at the same time; we would have never gotten anything done. We’d keep catching each other up all the time, because we’re old mates.