http://www.youtube.com/watch?v=RKuWJgUuLsY Go to 4:25 Near the end of the 11th he hits Castillo with a cross and Castillo goes down, Castillo's trainer smartly runs into the ring cuz he saw him legitimatley go down and knew the ref missed it and didn't wanna give the him time to re-think it.
I saw a looping right land flush and Castillo go down. In the post fight interview Casamayor also claimed he KD'd him in the 11th.
Castillo hadn't been hurt or KD in any fight before, It's a big deal big that Casamayor dropped him. Hell, even though Corrales TKO'd Castillo he never dropped him.