LAS VEGAS (AFP) - Filipino champion Manny Pacquiao added another world title to his growing collection by dethroning David Diaz in a World Boxing Council lightweight bout at the Mandalay Bay hotel on Saturday.

Pacquiao floored Diaz with 36 seconds left in the ninth round to end the fight, becoming the first Asian to win titles in four different weight classes.

"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."

Pacquiao (47-3-2, 35 KOs) used his quickness and superior boxing skills to dominate the bigger Diaz who suffered just the second loss of his career.

Although his WBC junior lightweight belt was not on the line, Pacquiao went on the offensive immediately and opened up cuts above Diaz's right eye and across the bridge of his nose.

Pacquiao put an end to the carnage in the ninth round with a left jab which caught Diaz on the chin and sent him to the canvas.

"Did anybody get the number off of that truck?" Diaz said. "Today is the day that we lost. Tomorrow is another day. He's fast. The speed was the difference in the fight. I have all of the respect for him."

The 29-year-old Pacquiao recorded his eighth-straight victory since losing to Erik Morales in March 2005. Included in that winning streak is a pair knockout wins over Morales.

The 32-year-old Diaz was making the second defence of his title after winning a unanimous decision over Morales last August, a verdict which sent the Mexican star into retirement.

On the undercard, Francisco Lorenzo claimed a controversial victory by disqualification over Humberto Soto to claim the interim WBC super featherweight title.