Are left handed have an advantage?

Just curious, true or not? If true, then what advantage do they have? Some interview: http://www.********boxing.com/news.php?p=24482&more=1 - it's "east side boxing . com" MAYWEATHER: I will be honest with you. A lot of times what these people do, it don’t make a difference. There are a lot of guys Floyd can fight. Well not a lot, but you got the African guy Pacquiao fought. Little Floyd could fight him. Like I said, little Floyd can fight Cotto, little Floyd can fight Margarito. Floyd can fight other fights. JENNA: Martinez or Williams, maybe? MAYWEATHER: Who? JENNA: Martinez. Sergio Martinez, the middleweight champ. MAYWEATHER: Is he a middleweight or a junior middleweight? JENNA: He’s currently the middleweight champion. MAYWEATHER: Oh yeah, yeah. He fought Kelly Pavlik. Okay. Yeah, yeah, yeah. I think little Floyd will beat him, too. But then again he’s left handed. I have to really see Sergio again. I have to see him again. It’s been awhile since I saw him. I have to see him again, but he’s another prospect, too, yes. http://**********.com/pag/article.php?aid=20777 - it's "boxing talk . com" SE: I have heard that your brother, Big Floyd, does not like your nephew, Little Floyd, to fight southpaws, and Big Floyd is the real reason why the mega fight has not happened. JM: "Big Floyd has always felt that way about southpaws, but he does feel that Lil Floyd will beat Manny. The real reason the fight has not been made is because Manny has not agreed to random blood testing."