Can anyone tell me why KK's beating Superman in this scan?

I've never read this comic so can anyone tell me why he's beating Superman? Isn't Karate Kid a human? How was he able to take down Superman?

http://img.photobucket.com/albums/v214/SaintSaturn/2000721765415603690_rs.jpg

@isaaclian11 BASICALLY, his martial arts abilities cause him to focus his hits, kicks, etc. so that even superhumans get destroyed. He's a beast.

Not to mention, I'm not sure if it's for Pre Crisis, but Post Crisis Superman is vulnerable to Chi.

Yeah, that too.