Pacquiao is rated as the best pound-for-pound boxer by Ring magazine
Manny Pacquiao became a four-weight world champion in Las Vegas on Saturday night, stopping David Diaz in the ninth round to win the WBC lightweight title.
Pacquiao dominated the fight, winning every round and opening a gash above Diaz's right eye and nose early on.
The 29-year-old Filipino finished the fight with a vicious left jab that sent Diaz to his second defeat.
Pacquiao, widely regarded as the world's best boxer, could be a future opponent for Amir Khan.
Prior to beating Manchester's Michael Gomez in a bruising encounter, Khan stated he wanted to fight the winner of the Pacquiao-Diaz fight, claiming he could "beat them both".
However, after an unconvincing performance the Bolton fighter's camp have moved to cool talk of a potential world-title fight, with Khan himself admitting he was not ready.
In winning his first belt at the weight, Pacquiao took his record to 47 wins from 52 fights, the most recent of his three defeats coming against Erik Morales in 2005.
Pacquiao avenged that defeat with two knockout victories over the now retired Mexican great.
And Pacquiao could potentially move up to a sixth weight, with a fight against Manchester light-welterweight Ricky Hatton rumoured to be in the pipeline.
"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."
Of Pacquiao's future, promoter Bob Arum said: "We will defend the WBC lightweight title later this year.
"There is a possibility we could fight Ricky Hatton next year. That remains to be seen."
Meanwhile, Steven Luevano retained his WBO featherweight belt after he drew with Mario Santiago.
After 12 rounds, each fighter won the backing of one of the three judges, with the third judge scoring the fight as even.