Venus and Serena Williams will meet in the semi-finals of the Family Circle Cup in Charleston following their respective quarter-final victories on Friday.
It will be the 24th time that the sisters have played each other in singles competition, with world number one Serena currently leading their head-to-head record 13-10.
Venus defeated fellow American Madison Keys 6-4 6-4 in her quarter-final tie, while Serena saw off Lucie Safarova 6-4 6-1.
The pair's last encounter came in 2009 when Serena defeated her elder sibling in straight sets to win the WTA end-of-season championships in Doha.
