There is definitely a chance for a surprise victory. Lindsay and Serena are out, Pierce could be as well.
Off the top of my head, I can see Venus, Hingis, Clijsters, Sharapova, Kuzy and maybe Henin reaching the quarters (obviously dependant on their draws). Other than those players, there aren't really any consistent slam performers at the moment and there should be at least 3-4 places in the QF for some younger players.
Casey Dellacqua, Jelena Jankovic, Anna-Lena Groenefeld,
Jelena Dokic, Mirjana Lucic, Sara Tomic, Sloane Stephens
Melanie Oudin, Kiki Bertens, Kaia Kanepi, Alison Riske