Mark Ronson has revealed he was a "totally blindsided" when X Factor contender Fleur East sang his new single, Uptown Funk, five weeks before its release date.
The song, which features Bruno Mars, was originally scheduled for release on January 11. However, Mark was forced to bring the release date forward by over a month after Fleur performed it on The X Factor.
Speaking to the Evening Standard, the songwriter claimed that the first he heard about it was from Twitter, as Simon Cowell did not not ask his permission for Fleur to sing the track.
He said: "I had no idea she was going to perform it. I was totally blindsided.
"I saw it in my Twitter timeline - a friend tweeted it during the show. I haven't been in England so I haven't watched the show or anything. I was like, 'What does he mean? That's weird!' You think we'd have some kind of sign off on it."
"Then I kind of twigged - don't they put out the songs on X Factor on iTunes that night? That's when I just had this pit in my stomach... I was like, 'Man - I hope the label over there knows what they are doing! Because this girl's about to have a big hit with our song!'"
But the 39-year-old DJ and songwriter has admitted that "it feels great" to have his first UK number one single, and things have turned out for the best. "Everyone kind of ended up with what they want. I got to have the record out, X Factor, the girl, she had her moment ... It's been a crazy week," he said.
Mark also feared the performance could have ruined his chances of success with the song, but his version went straight to number one in the UK charts on Sunday.
Speaking to NME, Mark said he'd feel guilty if Uptown Funk took the number one spot for Christmas though. He said he "always assumes Christmas number one will be the Pogues or Rage Against the Machine" and that he wishes "he had enough time to make a Christmas version of his single". The Christmas number one will be decided on December 21.
Mark Ronson's new album Uptown Special is due for release on January 19, 2015.