Sure, Hradecka will be the favorite here for many reasons, but Petra is surely not without a chance to win. They've played twice before, of course we know that Hradecka won this year in QR1 of Brisbane (straights), but Petra is a lot better now than she was back then (ranked almost 50 spots higher).
But the other match happened back in '07, when a certain 16 y.o. ranked 1032 in the world beat the 8th seed of Makarska challenger in the first round, and it was 6:0, 6:2 (the kid was Petra, the seed was Hradecka)! So Petra definately has what it takes to win. Sure, both of them have advanced immensely since then, but this year their respective results are about the same and they're almost ranked the same as well.
Hradecka got to the semis of Memphis by beating two barely top100 players and eventually losing to #105 - Petra got to the semis in Bogota by beating two top100 and one top50 player before losing to #77. Hradecka won a 100k in Midland, and Petra got to R2 from qualies in Melbourne (where Hradecka lost in R1 to Brianti). Hradecka played two tournaments more and qualified for more of them (3), while the highest ranked player she beat all year is Dulko at #48 (4 & 4) - Petra's best win was over Hercog at #49 (2 & 3).
So all in all, this could be a tough battle, probably three sets, but I believe Petra can do it.