Simon Cowell would love to see his X Factor co-judges Britney Spears and Demi Lovato sing together.

The music mogul is currently preparing for the season premier of US TV talent contest.

Although the two songstresses are judging talent, Simon still wants to see them perform.

"I want to see a Demi/Britney duet! Why not?" he told ET Online.

According to Simon, fans will likely be surprised by Britney's sassiness in the judge's chair.

The singer reportedly has a lot of spunk.

"You know if you buy a dog, you expect it to lick you and then it bites you," he explained. "[Britney] just wouldn't say yes for people to like her."

Both Demi and Britney are not pushovers.

Simon was impressed by their feistiness.

"They're like having two racehorses who are very talented, but difficult to control," he said. "I have a habit of working with annoying people. Demi brought that again this year in bucketloads."

The first episode of the new season of The X Factor airs in the US next week.