He is pound for pound the greatest boxer in the world. An eight-time world champion, the 147-pound Filipino fighter has obliterated his way through weight classes on his way to becoming a national hero in the Philippines and an international superstar.
The southpaw has crushing punching power, and his team has worked hard to develop a right as devastating as his left. But Pacquiao is packing a secret weapon when he walks into the ring - a deep abiding faith.
"The most important thing is to believe in God," Pacquiao said during a recent train trip to Washington, D.C. With his wife by his side and his team taking up the entire private train car, Pacquiao spoke to CNN about his faith, politics and his upcoming fight.
He was heading to Washington to meet with Senate Majority Leader Harry Reid. Last fall, Reid was down in the polls in a tough re-election fight, so he called in Pacquiao for a last-minute rally. On Tuesday in Washington, Reid said it was Pacquiao who helped put his campaign over the top.
Pacquiao is cagey but diplomatic when talking politics but lights up when asked about his faith. It is a big part of his life as a boxer.
When the 32-year-old Catholic bounded into the ring before his latest pay-per-view match, a silver rosary bounced on his chest as he hopped in place getting ready for the fight. He looked skyward and crossed himself.
It's a familiar scene to those closest to him. "He crosses himself before each round," longtime Pacquiao trainer Freddie Roach said. "After every workout we end it with a prayer. He's very dedicated to his faith."
Pacquiao (L) receives communion during a Thanksgiving mass at the Quiapo church in Manila on November 20, 2010
Manny Pacquiao, prays during a church service in Manila
And his story in the ring is one for the history books. His trainer thinks he may not just be the best pound-for-pound fighter today but the best pound-for-pound fighter ever.
"Eight world titles will never be duplicated. That makes him the best," Roach said. "That achievement will never be touched again, the caliber of fighters he's fighting, and his competition is great. And he's defeated all of them."
Manny Pacquiao celebrates after defending his title.
Those talents have propelled him to be the face of boxing, not only in the U.S. but also around the world, according to Arum.
"His story has resonated because he's been able to fight his way out and become the person he is, and instead of turning his back on all that growing up, he embraces that," Arum said.
Pacquiao has taken home millions upon millions for his bouts. By some estimates, he has amassed more than $70 million from his boxing alone. That amount does not include his other business ventures or endorsements.
"(Pacquiao) gives so much money to charity and is such a caring person. And he does so many good works, most of which is not publicized so you don't even know about it," Arum said.
For Arum, that charity is a tangible example of Pacquiao's faith. "He's constantly calling me on the advances, on the upfront of his purse and so forth, because he spending the money on good things."
For Pacquaio it is clear he believes his success comes from God. "Everything that I have done, that is possible in my mind, He has made possible."
Arum and Roach both say Pacquiao's faith in God is as helpful to him in the ring as his lighting-fast fists and quick feet. Arum said Pacquiao sees himself as part of God's plan, laid out in front of him so nearly nothing bothers him.
"When he lost to (Erik) Morales he said he knew it was God's decision," Roach said. "He accepts it well." That was the last fight Pacquiao lost, in 2005. He went on to beat him two more times after that.
And that ability to move on quickly has paid big dividends.
As he looks ahead to his May 7 fight in Las Vegas against Sugar Shane Mosley, the expected boxing bravado and trash talk is noticeably absent from Pacquiao.
"I'm not going to say I'm going to win yet because the fight isn't done yet. I just need to train hard and believe in God," he said.