So I just watched Rocky Balboa, the last Rocky movie which was released last year. Frankly, not so great. But as I was watching it I remembered something I had seen on TV while visiting my parents once. A little segment on ESPN or something about the boxer that Rocky was based on, Chuck Wepner.

Against all expectations, Wepner managed to knock down Ali, felling him in the ninth round with a right hand to the ribs. The referee Tony Perez ruled a knockdown; the fight commentator thought that Ali had simply tripped over his own feet, coincidentally timing with Wepner’s punch. In any case, this made Wepner the only boxer to knock down Ali while he was the reigning heavyweight champion of the world. – Wikipedia: Chuck Wepner

And here is the final round of the fight.