How many prime undefeated fighters has Pac-Man beat?

No one is disputing his future hall of fame status but is this the first prime (slightly injured) undefeated champion he is facing?

How is an undefeated Tim Bradley style different from Keith Thurman?

If manny beats an undefeated Thurman at 40 years old then this will truly set up a mega fight against Crawford or Spence.