To be clear 10% of people on this forum think you are credible the other 90% think otherwise, this conversation literally proves it. Zoro fainted after the fight, he still won the fight.
If one person is standing while the other is down then the one standing is the victor, it's what most people on this forum allude to as common sense. The real duel was between Zoro and Killer.
So by that logic Luffy tied Doflamingo or by your logic lost to Doflamingo because he fainted as well