Barty hit five aces in the 85-minute quarterfinal against former No. 1 Williams and stretched her winning run to 10 matches. The Australian, currently No. 2, needs to win the tournament to overtake Naomi Osaka at the top the rankings on Monday.
Osaka lost to Yulia Putintseva in the second round on Thursday and needs to wait to see if she'll still be top heading into Wimbledon, which starts on July 1. Barty next faces Barbora Strycova in the semifinals. Strycova won an all-Czech clash over qualifier Kristyna Pliskova 6-2, 6-4.
Also, Petra Martic saved five match points as she defeated Latvia's Jelena Ostapenko 6-7 (4), 7-5, 6-1. The Croatian will face Yulia Putintseva of Kazakhstan or Julia Goerges of Germany in the semifinals.
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