Sam Smith is "s****ing" himself over the release of his Bond song.

Sam Smith's Bond track

Sam Smith's Bond track

The Grammy and BRIT Award winner will unveil his eagerly anticipated anthem 'The Writing's on the Wall' today (25.09.15) - which will serve as the main soundtrack for new movie 'SPECTRE' - and he admits the pressure to meet the high standard of previous Bond themes is "quite intense".

He said: "I'm sh****ing myself. With this song I don't care about it charting and things like that. I just care about doing the legacy proud.

"The pressure to deliver a Bond song that stands against all the rest feels quite intense."

The 23-year-old star's "top secret" Bond song has only been heard by a select few, including 'SPECTRE' director Sam Mendes, close friends and family, and of course, 007 star Daniel Craig.

Sam says filmmaker Mendes even had a hand in writing the lyrics to ensure the famous spy didn't come across too vulnerable.

He explained to The Sun newspaper: "I feel like my music can be very vulnerable and I wanted to have a touch of that with Bond and have him sounding more vulnerable than normal.

"With Bond songs you get to be as dramatic as you want. I got to get away with unbelievable string and brass sections -- I got to be a drama queen.

"Sam had a say in some of the lyrics I was writing and made sure Bond didn't sound weak, that he still sounded powerful."