It looked as if Hatton was hurt bad to the body either in that round or in the round before. I think that may be what really caused the k.o. I'll have to watch the replay, because I didn't record it, but I rememeber Floyd landing to the body and bending Hatton over with it. You could see Hatton hurt by it, and favoring his right side a little bit. He didn't look the same after that, and the pressure all but stopped.
