Yuo're just yapping...
He couldn't beat Kuma in one on one fight. He couldn't beat Oz in one on one fight. He couldn't beat Moria in one on one fight. He couldn't beat Enel in one on one fight.
Extends to Lucci.
Did you guys miss on the part where Zoro said that if he thought Luffy was weaker than him, he wouldn't follow him any more?
i was genuinely stating my opinion on those things, and this is a "what if" thread so pretty much everyone is just "yapping".
anyway, we don't know if he could beat them or not because luffy did it first. and by bringing up the idea of an "honorable mano a mano fight" i was referring to the bushido idea, thus= swords.
when zoro said he would never lose again he also said that the man who would be pirate king can't have under him a guy who won't be the greatest swordsman. so while zoro said he wouldn't respect luffy if he wasn't the strongest, he also expects himself to be the best if he continues to be one of luffy's nakama. this is the whole bond of friendship between the two of them, and why zoro so adamantly stood up to kuma in luffy's place.
so yeah, against people like lucci, who don't use swords, its up for grabs. but if it came down to it, and zoro was the only one left to fight lucci, i believe he would fight to the death to protect luffy's dream. and that's why i think he would beat that leopard-man down. but that's just my opinion.