You're thinking of the Juan Manuel Marquez fight. Morales edged out Pacquiao 115-113 on all scorecards the first time around, and there were no knockdowns.

My analysis of the fight:
The first fight was extremely close. Morales only won it by one round. He opened a cut on Pacquiao's eye with a nasty headbutt, but was ruled as a punch. I would say that cost Pacquiao a few rounds because he was reluctant to fight his style: volume punching. He was too conservative and he was losing rounds because of it. Also, look at their last fights. Morales just came off of an embarrasing loss to a not top-five super-featherweight Zahir Raheem. Pacquiao KO'ed former world champion Velasquez. He also showed that he has been working on his right jab and hook, unlike his straight-left-only punching against Morales in their first fight. He also has a better manager (Shelly Finkel) now and is more focused in his new closed-session training.

I say Pacquiao wins a close decision.