Brock Lesnar went down hard against kickboxer Alistair Overeem in the first round at UFC 141 last night. A few minutes later, he announced his retirement. The former heavyweight champion finished his own meteoric mixed martial arts career on a losing note at Friday's Ultimate Fighting Championship event. Lesnar retired from the UFC after Overeem stopped him with one vicious kick to the body at 2:26 of the first round in their ...