User blog comment:The Bonehead Skipper/Luffy's Battle of Legend/@comment-3060121-20111215050303

Since these fights only take days where the opponent is equally powerful, the first thought would be one of the supernovas, or supernova strength new world captain, or one of the main villains(Akainu, BB, etc) once he becomes that powerful. But since Luffy has defeated opponents who have seemed stronger at the beginning of the fight in shorter time, it's not likely that he will have a fight lasting days.