The 'Britain's Got Talent' star is lending her vocals to a recording of the late rock 'n' roll legend on his version of Christmas carol 'O Come All Ye Faithful', and she is convinced his ghost paid her a visit while she was performing the track in the studio.
She said: ''I do sometimes feel his presence when I sing the song. I think he would be excited if he heard it and he liked it.
''Duetting with Elvis was beyond my wildest dreams.''
Music bosses have combined her vocals with those of Elvis - who recorded his version of the Christian hymn in 1971 - to raise money for charity Save The Children, of which Susan is an ambassador of.
The 52-year-old singer is hoping to land the UK Christmas number one spot when the song is released on December 8, which could prevent this year's 'X Factor' winner from reaching the top but she has revealed it was her mentor Simon Cowell's idea for a collaboration with Presley.
Simon contacted Elvis' widow Priscilla Presley to get permission to record the track.
Susan said: ''My dad and my whole family were Elvis fans and she gave me permission.''
Meanwhile, Susan - who shot to fame in 2009 on Simon's show 'Britain's Got Talent' - has also revealed movie producers are currently in talks to create a film about her incredible life.
She teased: ''There are plans in operation for that, but that's for later on.''
His new album Underneath It All is out now.