By Mark Vester

A bitter exchange of words have gone back and forth between boxing's pound-for-pound king Floyd Mayweather, Jr. and UFC president Dana White.

The war or words began last week when Mayweather, during a telephone conference with the media to promote his May 5 fight with Oscar De La Hoya in Las Vegas, tooks shots at Mixed Martial Arts, UFC, and one of the UFC's biggest stars, Chuck Liddell.

"UFC ain't s---," Mayweather said. "It ain't but a fad. Anyone can put a tattoo on their head and get in a street fight. These are guys who couldn't make it in boxing. So they do (MMA). Boxing is the best sport in the world and it's here to stay. We should put Liddell against a good heavyweight, under Mayweather Promotions.  If Chuck wins, then I'll give him a million dollars out of my own pocket."

CBS Sportsline writer Denny Burkholder noted that during a Monday conference call to promote UFC 69, White shot back at Mayweather by offering a million dollars if Mayweather could sell more than 10 tickets without a fighter like De La Hoya as the opponent.

"You know, Floyd Mayweather just came out and said some stupid s--- about Chuck Liddell," White said. (He said) he'd pay a million dollars if Chuck could hang with a heavyweight boxer. How about if he pays a million dollars to see if a heavyweight boxer can fight MMA with Chuck Liddell? Or, even better, I'll put up a million dollars of my own money if Floyd Mayweather can sell more than 10 tickets without Oscar De La Hoya."