"I was literally blown away," beamed Sam. "That man has been my favourite singer since I can remember. I've always said if I could duet with anybody in the world, it would be Michael Bolton."
The last remaining contestant from the Over 25s got the shock of her life when Michael walked into the room. Having kept in contact following an exchange of tweets, Sam believed he was abroad, and was completely stunned to see him.
"You told me you were in Germany, you naughty man," laughed Sam.
The competition has been life-changing for the mother-of-two. "I've done things I wanted to do before I die, that I never imagined in a million years I'd actually get to achieve," she said.
Singing with a big band was at the top of that list and Sam admitted that it was her "favourite performance out of everything".
Mentor Sharon Osbourne took a step back from providing guidance on the performance after Sam said, "I don't want anybody to tell me what to do." She was determined, adding, "I want to do the counting, I want to command the stage."
Not focusing too much on the outcome of the competition, Sam is soaking in the experience.
"Whenever I get up to sing on Saturday nights, I don't want to leave," she said. "I want to do it all over again, every time. I could do a whole show."
Sam is looking forward to singing in front of even bigger crowds on the X Factor tour.
"I can't wait for the roar of the crowd. Mind you, they will all be screaming for Sam Callahan or Nicholas McDonald, but it will be so nice to be able to get up on the stage," she joked.