Johanna Konta (GBR) vs Shuai Zhang (CHN)
Anyone saying they picked this quarterfinal is likely a savant, a random number generator, or a liar. Both players have achieved more than anyone expected when the tournament started, and both players are presented with a unique opportunity to reach a Grand Slam semifinal or further perhaps changing her career forever.
In a situation such as this, I think the player who is less likely to self-destruct in an avalanche of errors is the one most likely to win. That leads to my prediction.
My Prediction: Shuai Zhang d. Johanna Konta 7-5, 6-4