Top-ranked Serena Williams ended a long and successful day for the Williams family to reach the Family Circle Cup semi-finals and set up their first sibling showdown since 2009.
Both sisters posted two victories on Friday.
Serena won her 13th straight match by defeating sixth-seeded Lucie Safarova 6-4 6-1 at the WTA event in Charleston, South Carolina.
Earlier, she topped Mallory Burdette 6-4 6-2 in a third-round match moved due to Thursday’s 7 1/2-hour rain delay.
Venus also had double duty, rallying past Varvara Lepchenko 6-2 4-6 6-2 before ousting 18-year-old Madison Keys 6-4 6-4 later on Billie Jean King Court.
The Williams sisters will go head to head for a spot in the final on Saturday.
They haven’t met in a tournament since the 2009 Tour Championships in Qatar. Serena holds a 13-10 lead, although they’re 1-1 on clay.