Serena Williams (1) vs. Karolina Pliskova (10)
Williams and Pliskova have met once before in 2014. The round of 16 stage at Stanford, Williams triumphed 7-5, 6-2.
Caroline Wozniacki vs. Angelique Kerber (2)
Wozniacki and Kerber have met 12 times, the most recent of which was in Beijing in 2015. Wozniacki has won on 5 occasions, whilst Kerber has beaten her semi-final opponent 7 times.