Simon Cowell (search) might tangle with Paula Abdul (search) on-camera — but he's defending his "American Idol" co-star amidst Corey Clark's (search) allegations that he and Abdul had an affair while Clark was an "AI" contestant in 2003.

"I've worked with Paula now for four years, and we've had our moments ... but she's there to offer support to the contestants, and I've never seen anything untoward in all of the years I've worked with her," Cowell says on Tuesday's "Live with Regis & Kelly."

Cowell, dubbed at turns "Mr. Nasty" and "The Merchant of Venom," doesn't hold back in criticizing Clark, the focus of last Wednesday's "Primetime Live" report on ABC.

Clark, Cowell tells Regis Philbin and Kelly Ripa, "managed to sing the worst song I've ever heard" on that show.