American trainer Freddie Roach predicted yesterday that Manny Pacquiao wll be the first boxer to knock out world champion David Diaz when they clash for the American’s junior lightweight crown on June 28.

Roach made the prediction after seeing Pacquiao’s physical and mental condition and overseeing the Filipino’s training since the champ arrived in Las Vegas two weeks ago.

“Manny came in here in pretty good shape,” said Roach from the Wild Card Boxing Club in Hollywood.

“I believe Manny will become the first fighter to knock David Diaz out,” Roach said.

There are four sparring partners helping Pacquiao work out three times a week and there’ll be two more sparmates who are scheduled to show up soon.

“When they arrive, I will be sending two guys home,” Roach said.

Diaz had actually suffered a stoppage loss — the only blemish in his record of 34-1-1 with 17 knockouts — against Kendall Holt in Connecticut in Feb. 2005. But while Holt was declared winner by eighth-round technical knockout when referee Charles Dwyer intervened, the decision to stop the match was said to have been premature.

“With his back to the ropes, Kendall Holt began ripping power shots at David Diaz, landing with terrifying accuracy,” wrote noted boxing scribe Alex Pierpaoli. “When several hooks go temporarily unanswered and Diaz tips back with his mouth open, Dwyer steps forward to stop the action.”

“Just as the fight was stopped, it seemed clear that Diaz was not hurt as first appeared and was throwing punches as Dwyer pulled Holt out of range and halted the bout at 2:26 of round eight.” said Pierpaoli.

Before the sudden ending, Diaz, who was decked with two seconds remaining in the first round with a left-right combo, had floored Holt down in the dying seconds of the seventh round.

Diaz is not actually anvil-chinned, having been dropped by Holt and Morales, and Roach believes that Pacquiao’s punching power will be too much for the compact brawler of Mexican extraction.

Since the Holt debacle, Diaz has stormed back with astounding success, leaving in his wake aching bodies of long-armed bomber Jose Armando Sta. Cruz and even Mexican legend Erik Morales, who was forced to retire after absorbing a severe beating last year.

Meanwhile, Bernie Bahrmasel, who handles the publicity for Diaz, said the 31-year-old Chicago native will leave for San Francisco Friday night in time for the following day’s public-media workout.

“We are taking the 8 p.m. flight out of Chicago so David can have a full workout in the afternoon (of Friday),” said Bahrmasel, who will also be joined in the trip by manager-trainer Jim Strickland and cornerman Mike Garcia.