LAS VEGAS -- Don't get Manny Pacquiao angry. You would not like him when he's angry.
So don't say something that's going to tick him off prior to a fight, especially if you are the eight-division champion's upcoming opponent.
According to Pacquiao's trainer, Freddie Roach, that sort of thing might just earn you a butt-kicking.
"Trash talking. Manny just doesn't like that. He's never done that. If there is any trash talking, then it's by me," said Roach, a five-time Trainer of The Year.
"If I predict a knockout, it's not trash talking, it's just because I have confidence in my fighter," said Roach. "But Manny won't say that he's going to knock anybody out because he respects everyone that he fights."
That certainly is true about five-time champion Shane Mosley (46-6-1, 39 knockouts), who, on Saturday night, will try to lift from Pacquiao (52-3-2, 38 KOs) the WBO welterweight belt.
Although Mosley has promised to dictate an all-action fight, Pacquiao has not perceived anything that has come out of the challenger's mouth as offensive.
That was not the case, however, on Dec. 6 of 2008, the last time the 32-year-old Pacquiao said that he entered the ring and fought with a disdain for an opponent.
That rival was ex-world champion, Oscar De La Hoya, whose face Pacquiao pummeled into a bloody pulp on the way to a brutal, eighth-round knockout that forced De La Hoya to retire on his stool.
"Going into that fight, when he signed the gloves before the fight," said Pacquiao, explaining his focused anger, "he signed them and he put 'I'm going to knock you out.'"
Although Pacquiao inflicted a vicious beating on De La Hoya, Roach said that there were points within the fight where Roach felt compelled to implore Pacquiao to inflict the damage.
"I said, 'Manny, it's your job to knock him out.' And I had to tell him because I saw him pull up and take it easy on Oscar," said Roach.
"But I reminded him, 'It's your job to knock him out.' And he went out and he did it," said Roach. "Manny sat down on his punches and started throwing hard shots and so forth."
Roach said, however, that Pacquiao's response against De La Hoya was in sharp contrast to that of his last bout -- November's one-sided, unanimous decision over Antonio Margarito for the since-vacated WBC junior welterweight belt.
"When I asked Manny to knock out Margarito, he chose not to," said Roach. "Manny said that there was no need to hurt him."
This, despite some pre-fight mockery from Margarito's camp concerning the physical health of Roach, who has Parkinsons' syndrome.
Instead, the deeply religious Pacquiao wished blessings upon Margarito -- "I prayed for him" -- before beating his rival senseless during much of their fight and easing up over the final stages.
"Manny Pacquiao, in the Margarito fight, he became friendly with Margarito," said Roach. "In the 11th and 12th round, Manny's asking him if he's okay, and Margarito was nodding his head, 'Yes,' to him."
Still, Pacquiao's hammering of Margarito was comprised of 474 total punches, with 411 of them being power punches. The resulting damage was that Margarito's eyes were nearly closed shut and his fractured right orbital bone required 75 minutes of surgery to repair.
"Manny told me after the fight, 'You know, this is a sport,'" said Roach. "He said, 'I was in complete control of that fight.' I did not have to hurt him.'"
But does Pacquiao have that killer instinct to finish off an opponent?
"I always have had an instinct in the fight -- that killer instinct," said Pacquiao. "Especially if I hurt the guy."
That assertion appears to have been evident during Pacquiao's knockouts of Ricky Hatton, and, Miguel Cotto, respectively, in the second and 12th rounds of bouts that took place in May and November of 2009.
Pacquiao said that he will do the same against Mosley if the opportunity arises.
"If the knockout comes, then it will come," said Pacquiao. "But I'm not looking for a knockout. What I'm just looking for and focused on is to fight good and to do my best in the ring."
Roach expects as much.
"Manny's working harder for this fight than any fight that I've ever seen. Why? Because he knows that this is not an easy fight," said Roach.
"Manny respects Shane Mosley and he knew from Day One that this was not an easy fight," said Roach. "Manny has watched Shane his whole life and he respects him. He knows that he can't cut any corners with this guy."
Ask when the last time he perceived an opponent to be as much of a threat as is Mosley, Pacquiao answered, "De La Hoya."
