LOS ANGELES — Manny Pacquiao and trainer Freddie Roach have spent the past two months trying to solve the biggest puzzle in boxing.

How does anybody hit Floyd Mayweather Jr., a fighter whose perfect career is built on being nearly impossible to touch?

Pacquiao and Roach will reveal their answer Saturday night, when the fighters meet in the richest bout in boxing history. But clues to a strategy for breaking Mayweather’s impenetrable defense were evident in Pacquiao’s final workout at Roach’s Wild Card gym in Hollywood on Monday.

Pacquiao was a whirlwind of motion from the moment he stepped in the ring, throwing dozens of punches in combinations against Roach’s mitts and chest protector. While Roach took a much-deserved break, Pacquiao shadowboxed across the canvas, peppering the air with hundreds of rapid-fire punches long after his workout could have been over.

“You can beat Floyd Mayweather if you outwork him and never give him a chance to do the things he does best,” Roach said. “Manny is punching real hard, but I want him to outscore (Mayweather) in every round. I think we can win a 12-round decision. We want to throw a ton of punches.”

Pacquiao is betting on aggression, activity and punch volume to defeat Mayweather. The eight-division world champion has trained fiercely to fight 12 rounds of nonstop offense against the pre-eminent defensive fighter of his generation.

“I’m not really looking for a knockout,” Pacquiao said. “We’re not looking only for a knockout, but for throwing a lot of punches, and also making sure that every round, we’re ahead on points.”

Pacquiao has built his remarkable career on otherworldly quickness and old-fashioned volume punching, both outmaneuvering and outworking nearly all of his opponents over the past 10 years. He has never faced a fighter with Mayweather’s skills in defense and counterpunching, but Roach believes Mayweather has never dealt with an opponent as relentless as the southpaw Filipino congressman.

“Our volume of combinations is much higher than Mayweather’s,” Roach said. “Mayweather waits for you to finish your combination and throws back with the big right hand or the check hook, and we’re not going to be there for that. We’re going to be in and out, and I plan on Manny outscoring him that way.”

Roach also seems confident Pacquiao can move better than Mayweather in a 12-round fight, a remarkable prediction based on observation. The trainer believes Mayweather’s legs will fade in the second half of the fight, particularly if Pacquiao chases him around the ring for the first half.

Evidence of the decline in the 38-year-old Mayweather’s legs is debatable, but Roach insists he saw it in Mayweather’s two most recent fights against Marcos Maidana. The hard-hitting Argentine seemed to land more clean shots on Mayweather than anybody in recent history.