Date: 3/31/1973
Game: Ali-Norton I
Watch it here

Muhammad Ali took a lot of punches in his career, but few were as damaging as the ones he suffered against Ken Norton. In a bout against Norton, Ali had his jaw broken (it's unknown when exactly during the fight it happened—Ali's trainer claims it happened in the second round, while Norton says he delivered the killer punch later in the fight). Regardless, Ali fought 12 grueling rounds, and even though he lost a controversial decision, that's respect in our book. Not that boxing's G.O.A.T. needed any more.