Or a protective spell on the Evil Overlord -- both can work the same way. You have to justify the loophole, perhaps by the way no magic can be absolute, but then, you've got your way to specify a protagonist.
Ta-da! You have the Evil Overlord curse the entire land so that no one born before his curse, and no one born after, can bring him down, and then the good guys just have to find the lucky duck who was born while he was pronouncing the curse, and lo and behold, you have your de-facto Chosen One.
There are more elegant ways, no doubt, but the reason the prophecy persists in spite of everyone who complains of its hackneyed nature is that it does get the story moving. Useful tricks like that are not to be ignored.