The UFC commentators really played it up that former heavyweight champ Cain Velasquez’s knee gave out and that was what led to his defeat against Francis Ngannou in the UFC on ESPN 1 main event Sunday night in Phoenix. However, this footage clearly shows it was an uppercut that caused Cain to buckle and then his knee gave out. After the fight Cain said he got too close too soon to Ngannou. And to his credit he did not try and attribute the loss to the knee giving out. After more than two years on the sidelines it was a tough break to have the former champ’s return end so quickly, 26-seconds to be exact. But Ngannou hits like a Mack truck and even one short shot can put down the man who has been called the greatest UFC heavyweight champion of all time. Take a look at how it happened.