This is so contrived as to be almost silly, but I just realized that if you squint hard enough Sybill’s original prophecy might have referred to Harry as the Dark Lord and Quirrell as the one who “approaches”.

The one with the power to vanquish the Dark Lord approaches ... born to those who have thrice defied him, born as the seventh month dies ... and the Dark Lord will mark him as his equal, but he will have power the Dark Lord knows not ... and either must die at the hand of the other for neither can live while the other survives ... the one with the power to vanquish the Dark Lord will be born as the seventh month dies ...

The “Defense Professor” is a persona, and in chatting with Harry Quirrell basically claims that he becomes whoever he’s playing the role of. The prophecy could interpret the creation of that persona as “birth”. “Mark” is ambiguous enough (in English it could just mean “notice”), and besides, the prophecy doesn’t say when he will be marked. And he certainly has powers Harry knows not; his weird doomy link with Harry (which we just learned gives him partial access to Harry’s mind) being only the most obvious example, and remarkable from the fact that Harry doesn’t seem to ever think about it.

Again, it’s quite contrived, but it could be a nice twist to pull on your readers, though I assign a very low probability that Eliezer would do that given his statements.