Roach says that Mayweather's legacy will be blemished if he does not fight Pacquiao at least once and adds that Mayweather is very afraid of getting the first loss of his career against his name when/if the two clash in the ring.
"He's so in love with that zero on that record," Roach said to Jim Lampley on his program Fight Game.
"If he retires, not fighting Manny, that will be a big question when he's asked for things.
"I think that will ruin his legacy," Roach said.
The trainer feels that it would be fantastic if the two boxing superstars could meet in the ring more than once in a series of super fights.
"Possibly we'll do a multi-fight contract. I thought that was the best idea in the world," Roach said.
"I'd love to see these guys fight more than once, if they split the first two, then the third could be a rubber match, and we'd have three big fights," he added.