I dont see why so many people are torn on this. Yes Cain did hurt his knee, Yes he screamed and yes he couldn't continue... He didn't slip on a banana peal, he got cracked on the chin by the hardest hitter in the sport and his legs gave out. Its pretty simple, if cain didnt get punched so hard that he lost control of his legs, he wouldn't have hurt his knee. We can go even further...he said him self a take down early wasnt going to work. What the fuck was he doing using the same plan he said wouldn't work lol. Even "prime" cain had a suspect chin and a style that would lead to this result. I mean this shit happened in 26 seconds in one of the very first exchanges, his chin was never going to hold up even if that uppercut didn't land. This was just a really bad match up for Cain, any version of Cain.