Simon Cowell has lost $20,000 in a bet with L.A. Reid.

'The X Factor' USA mentors reportedly placed the wager at the beginning of the second series - which came to an end on Thursday (20.12.12) - that one of their act's would be crowned the winner, which would see the victorious judge win $20,000.

A source told gossip website that the 53-year-old British judge lost the bet when L.A.'s act Tate Stevens - who was in the over 25s category - received the highest number of public votes and announced the champion.

But the insider insisted that Simon hasn't displayed any signs of being a sore loser and plans to send his rival - who recently announced he would not return to the reality series next year after two seasons on the judging panel - a cheque as soon as possible.

Simon Cowell recently insisted L.A. is already regretting quitting the show to concentrate on his job as chairman of Epic Records.

However, the 56-year-old record producer - who is joined on the panel by Simon, Britney Spears and Demi Lovato - knew he would only make a short-term commitment to the series, but will continue to work with the 'X Factor' boss on other projects.

He explained: ''I came into this knowing that it wasn't gonna become my life.

''Simon and I are really good friends, and he knew at some point I needed to get back to work.''