The 19-year-old German, ranked 99th on the WTA Tour but who reached the quarterfinals at Memphis is March, also upset the Slovenian in the first round at Wimbledon.
While it took three sets, including a marathon 16-14 final set at Wimbledon, Goerges needed only 1 hour, 14 minutes to subdue Srebotnik on Thursday.
Top-seeded Maria Kirlenko won her second consecutive match in straight sets, beating Italy's Roberta Vinci 6-1, 6-2 to reach the quarterfinals.
Kirlenko, who needed 62 minutes and fought off all four break points in a 6-1, 6-1 victory over Nika Ozegovic on Tuesday, needed 15 minutes more to subdue Vinci. She converted six of 15 break opportunities and capitalized on Vinci's five double faults.
Qualifier Elena Bovina also scored another upset, beating Frenchwoman Camille Pin 6-3, 5-7, 7-6 (6) to advance to the final eight.
Also reaching the quarterfinals was eighth-seeded Sara Errani of Italy, beating compatriot Mara Santangelo 6-2, 6-4.
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