MANILA, Philippines -- Bob Arum thought he?d seen them all, until Manny Pacquiao came along.

The 76-year-old world renowned promoter, who has worked with the likes of Marvin Hagler, Oscar De la Hoya, Thomas Hearns, Sugar Ray Leonard, Evander Holyfield and George Foreman, saw Pacquiao in training recently and was visibly impressed.

?I have never seen any fighter train so hard for two hours without taking one break,? Arum told Sports Radio in a recent interview. ?I haven?t seen anything like this in 42 years.?

Arum was referring to Pacquiao?s continuous, absolutely-no-breaks, training session he witnessed recently at Freddie Roach?s Wild Card Gym in Hollywood.

?I asked Freddie how he does it. Everybody takes a break. Even Marvin Hagler takes a break. Manny? He never stopped even for one minute. He?s training like a man possessed. He?s in such a shape that he?s not human,? Arum was quoted by Johnny Benz of Doghouse Boxing as saying.

Though familiar with Pacquiao?s gruelling workouts, Arum still marveled at the way the Filipino ring icon sweated it out like he enjoys self-inflicted pain and physical torture.

?If he was unhappy while he was doing it I would be concerned,? added Arum, who?s co-promoting Pacquiao?s rematch with Mexican World Boxing Council super featherweight champion Juan Manuel Marquez on March 15 at the Mandalay Bay Resort & Casino in Las Vegas, Nevada.

In their first showdown in May 2004, Pacquiao knocked down Marquez three times in the first round but had to settle for a controversial draw.

The media will have a first-hand view of what Arum saw when Pacquiao holds an open workout on Wednesday at the Titanium Training Center in San Francisco, California.

Marquez-Pacquiao II is being co-promoted by De La Hoya?s Golden Boy Promotions, and will be distributed live by HBO Pay-Per-View.