Is Floyd Mayweather vulnerable to southpaws?On SI Now, Sports Illustrated senior writer Greg Bishop discusses if Manny Pacquiao has an advantage over Floyd Mayweather as a southpaw.SI Staff|Share on FacebookShare on XAdd us as a preferred sourceOn SI Now, Sports Illustrated senior writer Greg Bishop discusses if Manny Pacquiao has an advantage over Floyd Mayweather as a southpaw.Loading recommendations... Please wait while we load personalized content recommendationsPublished Apr 22, 2015 | Modified Apr 22, 2015SI STAFFShare on FacebookShare on XHome/Boxing