Had he been watching, Mayweather might have been as stunned at what he saw as his estranged father seemed to be in Ricky Hatton's corner. Fighters just aren't supposed to do the kind of things Pacquiao did to Hatton in 5 minutes and 59 seconds of utter domination before a thrilled crowd at the MGM Grand hotel.
All Mayweather can do now is get in line. The road to greatness now runs through a fighter who truly does let his fists do the talking.
"If Mayweather wants a piece of the little Filipino, just be my guest," promoter Bob Arum crowed when it was all over.
That's not likely to happen right away, but the odds are good it will happen eventually. There's too much money involved for it not to.
But give Pacquiao Round 1 already. On a day when Mayweather tried to steal his thunder by unretiring, Pacquiao went into the ring and showed why he is the most exciting thing to happen to boxing in a long, long time.
He didn't just beat Hatton. Didn't just knock him out.
He demolished a world class fighter who had never lost at his natural weight of 140 pounds, and he did it with such precision and ease that the talk afterward wasn't whether Pacquiao is the best pound-for-pound fighter in the world, but whether he might be one of the best ever.
A right hook - a punch most southpaws don't even have - started it all, dropping Hatton midway through the first round. A left cross that may be one of the greatest single punches ever thrown in a big fight ended it with a dramatic flourish.
When it was over, Hatton was sprawled motionless on his back in the center of the ring. Pacquiao and his corner were celebrating and the sellout crowd was trying to digest what they had just seen.
And Mayweather was at a bowling alley somewhere trying to pick up a spare.
A few hours earlier, Mayweather had declared that "The king is back" and said he was ready to reclaim his title as the best pound-for-pound fighter. But boxing has a new king in an unassuming fighter so good that he won his last four fights in four different weight classes.
It's a remarkable story even in a sport where tales of rags-to-riches are commonplace. There was a time when Pacquiao lived in a cardboard shack in his native Philippines, and there didn't seem anything special about him when he fought his first fight there at 106 pounds in 1995.
But he began growing and started knocking people out. He hooked up with trainer Freddie Roach and learned how to use his right hand as well as his left.
He sent Oscar De La Hoya into retirement, and may have done the same to Hatton.
And he's such a hero at home that there's talk of him running for president.
Boxing fans have responded by embracing Pacquiao, filling every seat at the MGM Grand and spending $49.95 for the pay-per-view to watch him fight from home. With good reason, because he gives fight fans what they want to see.
While Mayweather plays the villain with great success, Pacquiao comes across as a humble fighter who cares about nothing except doing his job, then getting together with his band as he did after stopping Hatton to make some music. He's fairly fluent in English and makes a point of speaking it instead of relying on a translator, and he acts like a professional in everything he does in boxing.
Most importantly, though, he comes to fight. Oh, does he come to fight.
"He has the opportunity to become the best I've ever promoted," said Arum, who promoted Muhammad Ali and Marvelous Marvin Hagler among others. "Other fights reach a certain level and they think they know everything and never get better. Not Manny. He's always learning."
Pacquiao brought his mother over from the Philippines for her first trip to the United States, but she couldn't bear to watch her son fight. Instead, she stayed in a hotel suite praying for his success and health.
The rest of us were watching closely, though.
And there was a lot to like about what we saw in the new king of boxing.
Tim Dahlberg is a national sports columnist for The Associated Press. Write to him at firstname.lastname@example.org