Maria Sakkari saved four match points as she battled past Elina Svitolina to reach the San Jose semi-finals.
Simona Halep played a brilliant decider to power past the considerable challenge provided by Alja Tomljanovic.
Victoria Azarenka, Johanna Konta, Maria Sakkari and Kristina Mladenovic have made significant strides at the Italian Open.
Maria Sakkari won her first WTA title in Rabat as she defeated Johanna Konta in three sets.
2018 Champion Kiki Bertens crashed out of the Volvo Car Open in the third round with a straight-sets loss to Maria Sakkari.
Johanna Konta led by example with a battling display to see off Greek No.1 Maria Sakkari and secure victory for Great Britain.
A win on Sunday would be the biggest ever for either player.
Karolina Pliskova loses 3-6 6-3 7-5 to Maria Sakkari in a huge upset in the second round of the Italian Open, while Halep thrashes Osaka.
The Greek No.1 has gained some extra funding thanks to a selfless good deed from his compatriot.
It was a busy day all-around for two-time champion Venus Williams but a routine one at the office as she powered past Greek Maria Sakkari 6-3,...
American qualifier Jennifer Brady and serial upsetter Mirjana Lucic-Baroni both make 4th round, while 16th seed Barbora Strycova keeps on marching on to the 4th round...