Jean-Claude Van Damme doesn't just talk the talk when it comes to MMA fighting -- he's a REAL athlete who coulda competed in the UFC back in his prime ... so says Roy "Big Country" Nelson.
Roy isn't just an accomplished UFC fighter in his own right -- but spent some quality time with JCVD on the set of the upcoming "Kickboxer: Vengeance" flick.
And with Van Damme recently lecturing UFC fighters about how weak their leg strikes have become -- we had to ask Roy if he thinks JC could back up his tough talk.