Karolina Pliskova and Marketa Vondrousova will face off for the first time in the first ever Miami quarterfinal between players from the Czech Republic today. Pliskova holds a 21-6 lifetime record against her compatriots in WTA main draws, including the last 12 and 17 of the last 18; the only time she has lost to another Czech since June 2016 was in last year's Madrid semifinals, to Petra Kvitova. Vondrousova, meanwhile, is 3-0 against fellow Czechs in WTA main draws, including a first-round win last week over Barbora Strycova.
World No.2 Simona Halep will face Wang Qiang for the second time, having previously defeated the Chinese No.1 7-5, 6-1 in the fourth round of Indian Wells last year.
Karolina Pliskova and Marketa Vondrousova are both enjoying consistently excellent form in 2019: Pliskova has reached at least the quarterfinals of every tournament she has played and is 15-3 in WTA main draws, while Vondrousova has backed up her second WTA final in Budapest with her first back-to-back Premier Mandatory quarterfinals in Indian Wells and Miami, taking her win-loss record this season to 13-3.
Wang Qiang is bidding to become the first Chinese semifinalist in Miami since Li Na's run to the 2014 final, and to make the last four of a Premier 5 or higher event for the third time in her career following back-to-back semifinal showings in Wuhan and Beijing last year.
Both Simona Halep and Karolina Pliskova are competing in the fourth Miami quarterfinal in the past five years, and both are bidding for their second semifinal here: Halep reached the last four in 2015, losing to Serena Williams, while Pliskova's previous best showing was her semifinal run in 2017, where she fell to Caroline Wozniacki.
19-year-old Marketa Vondrousova is the youngest player left in the draw, and the first teenage quarterfinalist in Miami since Caroline Wozniacki in 2010. Vondrousova is aiming to become the youngest semifinalist here since a 19-year-old Victoria Azarenka in 2009.
Following Petra Kvitova's quarterfinal loss to Ashleigh Barty, Simona Halep now just needs to reach the final to regain the World No.1 ranking from Naomi Osaka. Meanwhile, Wang Qiang will hit a new career high in Monday's rankings, and Marketa Vondrousova is guaranteed to return to the Top 50 just over a year after first breaking it.
ORDER OF PLAY (all courts start 1pm)
WANG Qiang (CHN)  vs Simona HALEP (ROU) 
After 2 ATP matches, not before 7pm
Karolina PLISKOVA (CZE)  vs Marketa VONDROUSOVA (CZE)
Samantha STOSUR (AUS) / ZHANG Shuai (CHN)  vs Monica NICULESCU (ROU) / Abigail SPEARS (USA)
Not before 2pm
[WC] Victoria AZARENKA (BLR) / Ashleigh BARTY (AUS) vs Darija JURAK (CRO) / Raluca OLARU (ROU)
Elise MERTENS (BEL) / Aryna SABALENKA (BLR) vs Gabriela DABROWSKI (CAN) / XU Yifan (CHN)