He may be known as a "great Scot" in some quarters, but the Great American Songbook has been very good to Rod Stewart.

The 59-year-old singer has recorded two back-to-back collections of American standards and they have been among his most successful recordings in recent years. Last year's As Time Goes By ... The Great American Songbook, Vol. 2 and 2002's It Had To Be You ... The Great American Songbook, have sold two and four million copies, respectively.

"To sing -- it's glorious," said Stewart during a recent interview prior to his arrival at the Air Canada Centre tomorrow night. "I mean, I don't know why these albums are a big success 'cause a lot of great singers have done these songs before me. The only spin I can put on it is that my sort of contemporary voice singing these old songs. It was just a lucky collaboration."

That Stewart is able to sing at all is a minor miracle after his throat was operated on in 2000 when cancerous polyps were discovered.

"After the operation, I had to lower the keys of all the other songs so the voice is a half a step deeper than it was before the operation. So I think that gave me a sweetness," said Stewart. "I think this was an album, I don't think I could have recorded 25 years ago."

Still, Stewart claims he suffered some initial nervousness about turning crooner.

"For obvious reasons, it was a real risk. You know, me -- a dyed-in-the-wool rocker suddenly turning to all these wonderful songs written in the '30s and '40s. You know I felt like I was almost being a rock-'n'-roll traitor but it's something that I've always wanted to do and I thought, 'Well, I'm at the age now where I should be able to do exactly what I want to do. I'm past pleasing other people.' So it started out as a labour of love."

Stewart said he avoided "Broadway type musical standards" from that era and went for songs with a strong lyrical content and an edge.

"I'm always comfortable if I know Billie Holiday's done it. Let me put it that way."

As for alienating old fans, he's not worried about it.

"You can't be an 18-year-old rock-'n'-roll star all your life and this was a big risk for me, and I took it and it's paid off. And I just hope the fans are pleased. A lot of my fans have grown up with me so they probably like all this stuff, when they're in a romantic mood."

And given that the name of Stewart's latest road trip -- his first in three years -- is From Maggie May To The Great American Songbook -- die-hard fans shouldn't be nervous that he won't be singing a lot of his old rockers in concert.

He's bringing an 11-piece band and 10-piece orchestra for the show that will see him combine the old rock classics with about a half-hour of standards.

"The American songbook, obviously, I'm not going to throw the microphone stand about," explained Stewart. "In the first set I'll go as mad as this old frame will let me probably."

Still, Stewart says his attitude toward performing has changed since he first began more than 35 years ago.

"I think I'm probably a lot more relaxed. I don't have to get s--tfaced drunk anymore, like we used to in The Faces. I enjoy entertaining. And I'm one of the few guys you'll find that actually enjoys being out on the road, although I miss me kids. I love live entertainment, as opposed to the studio. I'm not very good at being in the studio. I've got the attention span of a flea."