Pacquiao (54-3-2) didn't get the knockout he wanted, but the Filipino Congressman retained his position as the most dominant and exciting fighter in boxing, methodically beating Mosley (46-7-1) at the MGM Grand Garden in Las Vegas.
Pacquiao knocked Mosley down with a left hook in the third (3rd) round, a punch that seemed to sap Mosley's willingness to engage. Pacquiao ran after Mosley the rest of the fight, but the former champion Mosley who has never been stopped in 18 years in the ring managed to finish the 12th round on his feet.
Pacquiao won 120-108 on one scorecard, 120-107 on a second and 119-108 on the third. The Associated Press had him winning 118-110.
For Mosley, the fight was strikingly similar to his bout a year ago against Floyd Mayweather Jr. - except this time he didn't even land a big punch like he did early on against Mayweather.
His biggest moment on this night came when referee Kenny Bayless mistakenly ruled that Mosley knocked Pacquiao down in the 10th round when he hadn't even hit him with a punch. Manny Pacquiao slipped and fell down when Mosley stepped on Pacquiao's right foot and pushed him.
The ruling seemed to spur Pacquiao on as he went after Mosley the rest of the round and again in the 11th. By then, the crowd was cheering "Knock him out, knock him out," but Pacquiao - bothered by a cramp in his left leg since the fourth round - didn't have enough to finish him off.
"It wasn't my best performance," Pacquiao had. "I did my best. I did not expect this result."
Mosley said he thought he did a good job despite losing round after round, and wouldn't blame his bad performance on his age.
"I fought the best fighter in the world," Mosley said. "He has exceptional power, power that I've never been hit like this before."
Promoter Bob Arum defended putting Mosley in the ring against Pacquiao despite signs in Mosley's last two fights that his reflexes were slipping.
"Nobody can really perform against him," Arum said. "Some of these guys are pretty good fighters, but nobody in their whole experience has ever faced somebody like Pacquiao. Everybody is going to look the same way."
Mosley was tentative from the opening bell, moving backward and seemingly unwilling to trade punches with Pacquiao. Pacquiao finally made contact with a left hook at the end of the third round, sending Mosley to the canvas for only the third time in his professional career. Yahoooooooo!
Mosley was up at the count of five though, and managed to survive the final minute of the round despite Pacquiao's best efforts to take him out.
Pacquiao pressed the fight most of the night, but he also appeared hesitant to take many chances, which trainer Freddie Roach said was because of the muscle cramp that his corner tried to massage between rounds.
"He had no leverage to move after that," Roach said. "It was a very gutty performance in my mind."
Pacquiao said his leg first started bothering him in his fight last November against Antonio Margarito.
"I thought Shane did a great job, he had some speed," Pacquiao said. "I couldn't move because my left leg got tight. It's a problem I've been having lately. I'm going to work on my legs in future training camps."
The sellout crowd of 16,412 booed Mosley repeatedly in the late rounds for his refusal to trade punches with Pacquiao.
Mosley fought as if trying to protect his legacy of having never been knocked out and, if that was his strategy, it succeeded. But it made for a lackluster fight and did nothing to burnish the legacy that the Filipino champion has built with 14 straight wins over the last six years - including some over the biggest names in the game.
Oh well, they will be laughing their way to the bank. And us boxing fans, got to see pushing and running the whole 12 rounds. Geezz! Hayz!