Watch 24/7 Pacquiao/Marquez on CNN tonight at midnight ET.
(CNN) -- When one of his sparring partners said he was getting married, Manny Pacquiao helped the newlyweds buy a house.
When the poor province in which he grew up in the Philippines needed a hospital, he ponied up some of the money for one.
When his country had elections, Pacquiao ran twice for and finally won a post in congress. He helped start one program to give cattle to farmers and another to give small motors to fishermen for their boats.
No doubt, the boxing champ has a soft heart.
Except for one man, apparently: his opponent in Saturday night's HBO pay-per-view fight, Juan Manuel Marquez.
They have fought twice before. After fighting to a draw in the first match, Pacquiao won by split-decision in the second.
Marquez insists he won both fights. It's not unusual for a boxer to think he won a close match, but after a fight against Michael Katsidis last year, Marquez wore a shirt that said on the front, "Marquez beat Pacquiao twice!!" and on the back it said, "Pacquiao, Your (sic) Next."
Those close to Pacquiao say the taunt angered him. Some say he has prepared for this fight with an intensity they haven't seen from him before. Asked by reporters last week about the animosity, the boxer said:
"I have worked really hard for this fight ... and made a lot of sacrifices for this training camp," said the soft-spoken Pacquiao in halting English.
"If a knockout comes, that is a bonus for the hard work. I just wanted to make sure I was prepared 100% for this fight."
But trainer Freddie Roach admits that the T-shirt gave Pacquiao, rated by Ring Magazine as the best fighter in the world regardless of weight, an "extra spark." Pacquiao usually spars at 50% intensity, leaving some energy for the fight, said Roach. This time, during an extended 10-week training camp, the "Pacman" has upped it to at least 70%.
During a recent talk with one of his sparring partners after a workout, the 144-pound Pacquiao exclaimed, "I want this fight! I want this fight."
And earlier this week Pacquiao said Marquez had disrespected him and he was out to prove who was better, not for a huge payday.
Pacquiao, 33, will earn many millions for this fight against Marquez, an often overlooked superstar who is rated by Ring as the fifth-best fighter pound-for-pound. Depending on pay-per-view sales Pacquiao will make more than $30 million. (The fight, for Pacquiao's welterweight title, will be televised on HBO PPV, which like CNN is owned by Time Warner.)
Pacquiao's success in the ring and his generosity have made him a national icon.
"He came from extreme poverty," Bong Constantino, mayor of Malungon, told CNN's Talk Asia in 2009. "Now that he has everything in life he still practices that extreme humbleness in his heart. That's why he is so loved by our people here."
When he was young, Pacquiao sold candy and cigarettes on the streets. There were days he didn't make enough to eat. At 14, he ran away -- stowed away, actually -- to Manila to help earn more money for his siblings and single mother. At first he was a laborer, but he soon learned he could earn 100 pesos (a few U.S. dollars) fighting unsanctioned bouts -- the kind where the losers occasionally died.
Motivated by the death of a friend, Pacquiao eventually succeeded in turning pro. He won his first 11 fights, televised on Friday nights, making him a national celebrity.
But the big money was in the United States, and eventually with a 33-2 record and a super-bantamweight (122 pounds) title, he moved to America in 2001 at age 22. He and his manager flew to San Francisco and took a bus to Los Angeles where someone directed them to the Wild Card Boxing Club in Hollywood.
That's where Pacquiao met boxing-trainer extraordinaire Roach.
The two are a strong team, said long-time trainer Emanuel Steward, who will serve as an analyst for the TV broadcast.
"There is an unbelievable chemistry there," Steward said. "They really seem to understand each other. Freddie has done a great job with him."
That includes with letting Pacquiao be a free spirit when he's not boxing.
You would think Roach would be upset with all the things Pacquiao does outside the ring -- politician, game show host, businessman, pitchman -- but the trainer embraces it.
"I like the separation," Roach said. "He doesn't keep his mind on the fight all the time. When he gets in the ring, it's nothing but boxing. But if he wants to go on Jimmy Kimmel, if he wants to go sing, I have no problem with that. ...That's Manny Pacquiao."
Many Americans know of Pacquiao from the ring or his Hewlett-Packard commercials or his appearances singing on late night TV. But don't assume that just because he is the pound-for-pound best fighter that he'll easily handle Marquez, the WBC and WBA lightweight champion.
"Out of the 24 rounds they fought he's ahead by one point," Steward said. "Manny -- sometimes when he goes forward he's so excited, he almost runs in and he gets his legs crossed up. And Marquez catches him after that when Pacquiao is off balance."
Steward said Roach has made Pacquiao a better fighter, helping him improve his lead right hand. That combined with the fact that Pacquiao throws amazingly quick punches from "so many weird angles" leads Steward to predict a Pacquiao victory. Although he would be a very nervous bettor, he said, if he were to lay money down.
After the fight, it'll be back to work in congress for Pacquiao. It'll be every bit the battle as a fight in the ring, he said. Philippine politics are rife with corruption, he told CNN's Piers Morgan.
"That's what I am trying to do, to change politics in the Philippines," he said in an interview to be broadcast Friday night. "I want (to show) to them that I am the good example, to serve honestly."