"Crossing fingers, hopefully that fight will happen," Pacquiao said.
If it doesn't, the current world welterweight champion is positioned for a move back to the junior-welterweight class, where he believes his famed power will return.
Pacquiao (56-5-2, 38 knockouts) is defending his World Boxing Organization belt Saturday night against New York's Chris Algieri at a catch-weight of 144 pounds.
In a meeting with reporters on Tuesday, Pacquiao was at 143 pounds. He said he believes he could even trim down to 135.
From September 2005 through 2009, a year in which he savagely decked Ricky Hatton and then wore down current middleweight champion Miguel Cotto in a 12th-round technical knockout, Pacquiao won eight of 11 bouts fought between 130- and 144-pound weight limits by stoppage.
"The speed's still there, the power's still there, the hunger's still there," Pacquiao said. "Moving down in fighting weight is good for me."
Pacquiao trainer Freddie Roach has Mayweather as his No. 1 choice for Pacquiao's next foe, but he expects a dominant showing Saturday night (Pacific time) against Algieri, and says he'd "love" a Pacquiao fight against another unbeaten 140-pound champion, Danny Garcia.