Pac thrives vs Southpaws, as it seems much easier for him to get off his offence. Rigo is awful vs southpaws, as he seems to find it much harder to defend against them. Add in Pac's lethal punching power, and Rigo's suspect chin, and there's only really one option. Although I do think that Pac's chin at 122 was pretty average, which means Rigo could take him out on the way in, but I doubt it highly.