"I am happy for the win tonight. I never thought I would win four world titles in four different classes," Pacquiao said. "I feel great at this weight. I feel stronger at 135 pounds than at 130. He did hurt me one time during the fight. David Diaz is a very strong fighter."

As for his future, a fight next year against Manchester's light-welterweight Ricky Hatton is on the cards.

"We will defend the WBC lightweight title later this year," said promoter Bob Arum. "There is a possibility we could fight Ricky Hatton next year. That remains to be seen."

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