Michael Bublé says working with American country star Willie Nelson was career highlight

Bublé duets with 88-year-old Nelson on Crazy, the classic song first made famous by Patsy Cline and which Willie wrote back in 1961.

"I don't know if there's anyone alive who means as much to me because he is one of my few heroes that are left," Michael tells Shuffle.

"I hold him in the same regard as I hold Frank Sinatra, Dean Martin and Ella Fitzgerald. I know that might sound strange for people, but for me he's one of the greatest crooners and storytellers of all time."

Although Bublé knows Willie's son, Lukas, who is also a singer, he never asked to be introduced to his father or to request a collaboration.

"It's funny, I'm friends with his son, Lukas, and I have been for many years," Michael tells me. "But I never dared to cross that line. I thought it would be inappropriate."

He reveals that the collaboration with his musical idol eventually happened by chance. "It was a lucky thing," Michael says. "My producer, Bob Rock, came into the studio and I said, 'Bob here's the song Crazy, I want to do it more like Willie's version.' It was Willie's version that I was always more turned on to. God bless Patsy Cline, she's amazing, but Willie was my guy. He made the Stardust record (an album featuring Willie covering pop standards), and it was a big record in my life.

"Bob said, 'You know Willie is my neighbour in Maui. We know each other very well. Would you like me to ask if he'd play guitar on it. I said, 'Hell Bob, if you're going to ask then ask him if he'll sing… and he did!'

The pair instantly hit it off when they got together.. "Willie Nelson is a great character, a beautiful guy," Michael says. "But I don't know what was more of a joy, getting to know him or getting to know his wife, Annie. His wife is a special lady. They are just wonderful people. I was so lucky."

At this stage of his career, Bublé has definitely earned the right to work with the legends and his idols - and another is Paul McCartney who actually contacted Michael and asked him to consider recording his song, My Valentine.

The Canadian singer jumped at the chance. "It's an honour to be trusted with the art of a great man and a genius," Michael says. "I then asked Sir Paul McCartney to produce the record, not because of what he has done, but because of what he can do… and I think we made a beautiful record.

"Here's a song he wrote 10 years ago for his wife, Nancy, and it shows how prolific and imaginative and wonderful he still is. It was a song that nobody talks a ton about and I had a cool concept for it, and now it sounds like it could be among the greatest songs of the American Songbook… and if that isn't a testament to this man and his greatness I don't know what is."

Bublé says McCartney still has the passion of a teenager for writing and performing. "He loves it. He's fascinated by the creative process. I think he loves something coming from nothing.

"But what I found interesting about the whole damn thing was his genuine fascination in talking to people, and I mean not fancy people, but the punter on the street. The guy who would come and bring the coffee he would sit and talk to him. He's a genuinely inquisitive curious 18-year-old in the body of whatever age he is [80 in June].

"I feel like that about myself. I feel he and I have so much in common, except for the genius part," Bublé add with a laugh.

Michael Bublé's album, Higher, is out now.