He dominated the 9th round and the ref came to Horn's corner and told him the fight would be stopped if he didn't see anything from him.
Up to that point, personally, I thought it was pretty close. After that, Pac was gassed. Horn showed himself well the last 3 rounds.
I expected a close Pac decision. Guys are wound up because of the 117-111 scorecard and because the 9th round looked really bad for Horn.
Also, after the fight Pacman seemed to give 2 shits and quickly reminded everyone of the rematch clause if he lost, so it definitely looked shady. It was a great fight otherwise.