Who's got the balls to talk trash to LeBron James???? (besides Charles Barkley) ... how about the GREATEST competitor in the history of "The Challenge!!!"
TMZ Sports spoke with 'Challenge' legend Johnny Bananas ... who's DOMINATED on the MTV show for years ... and he strongly believes LeBron wouldn't stand a chance in his world.
FYI, "The Challenge" is a bunch of hot dudes and chicks who party their faces off and sometimes bang each other at night ... and then go to war in grueling physical competitions during the day. New season premieres tonight.
It's crazy ... these people are legit athletes.
So, we asked Johnny how a world-class physical specimen like LeBron would hold up. He ain't too confident in the King.