Crooner Engelbert Humperdinck has unveiled the "soaring ballad" that he hopes will restore the UK's reputation at this year's Eurovision Song Contest.
The 75-year-old sings alongside a Spanish-style guitar accompaniment in Love Will Set You Free.
Humperdinck will be joined on stage by guitarist James Bryan at the May contest, in a performance staged by choreographer and former Strictly Come Dancing judge Arlene Phillips.
The BBC announced earlier this month that Humperdinck was the surprise choice to represent the UK following years of disappointment, with boy band Blue coming 11th in 2011 and Josh Dubovie coming a humiliating last in 2010.
Humperdinck said that he had his "eyes on the prize" with the track, which was premiered on the BBC's Eurovision website.
He praised the ballad for its "quality and longevity" and called it "a beautiful romantic song".
"I have been called the 'King of Romance', I've represented romance all my life and have been a part of the business for 45 years. You can't pretend, it has to be within you," he said.
"Romance is what makes the world go around, when people hear romantic songs, they fall in love."
He said of the contest: "Nobody knows what will happen, but I'm going to do my very best."
Love Will Set You Free was recorded in London, Los Angeles and Nashville and has been written by Sacha Skarbek - who co-wrote James Blunt hit You're Beautiful and Lana Del Rey's Born To Die - and Grammy-winning producer Martin Terefe.
The song, which features the chorus "If you love someone/Follow your heart/'Cause love comes once/If you're lucky enough", has already received a mixed response.
One listener wrote on the BBC's Eurovision website: "It's 'Humperlicious!' - I was dead against when I heard he was to enter, don't know why! But as a true Eurovision fan - I am proud to support this."
Another said: "Amazing. Instantly memorable, fantastic original tune, meaningful words, tingle-factor, great performance... it sticks in the mind after only one hearing."
Another added: "My initial reaction to Engelbert was 'Oh No!' Having heard the song, it is now 'Oh Yes!' He still has the voice, can put it over, and the song is deceptively simple."
Others were not so keen, with one describing the song as "very poor", adding: "If you're not asleep before it, you will be by the time this has finished."
Another wrote: "I can't 'believe' in this song, won't be very easy for me to wave my Union Jack on the big night."
One added: "The lyrics to this song are utter drivel! As a professional songwriter... I can say this will struggle to get into the top 20 of the votes if we are lucky!"
Another criticised the ballad as an "embarrassment", saying "we will get zero points or close again!"
Perma-tanned heartthrob Humperdinck, whose hits include Release Me and The Last Waltz, enjoyed his last top 10 hit 42 years ago and famously held The Beatles off number one in 1967.
The veteran singer will be representing the UK at the 57th Eurovision Song Contest, which is expected to attract 120 million viewers, on May 26 in Baku, Azerbaijan,
Swedish singer Loreen has been tipped to win, while Humperdinck will also face competition for the grey vote from Russia's entrant, the Buranovo Grannies.
The last UK win was in 1997 when Katrina And The Waves - fronted by American singer Katrina Leskanich - took the honours with Love Shine A Light.
BBC creative director of entertainment Derek McLean said of Humperdinck's song: "It is a soaring ballad that has been crafted by some of the best people in music.
"With credentials like these, and our very own music legend on vocals, this year our Eurovision entry is second to none."