(CNN) -- Venus Williams is through to the semifinals of the Madrid Open with a straight set win over Samantha Stosur on Friday.
The elder of the Williams sisters, who will rise to number two in the world rankings next week, made light work of her Australian opponent with a 6-3 6-3 win, and is yet to drop a set in the clay court tournament.
In a match that lasted just over an hour, fourth-seeded Williams was dominant from the first point, breaking Stosur's serve three times and serving consistently well herself.
"I just felt like when we went on court I was focused on what I wanted to do today," Williams told the official WTA Web site.
"From 4-3 in the second set I felt like I went on auto-pilot and it felt really good."
The American is the highest ranked player left in the draw and must now get past Shahar Peer of Israel, to make it into Sunday's final.
Meanwhile, Nadia Petrova, the conqueror of the younger Williams sister Serena in the previous round, was defeated by the Czech Republic's Lucie Safarova.
Petrova won the first set 7-6 but could not maintain that standard, losing the second and third set 1-6 6-7.
Safarova continued the fine run of form that saw her breeze past Maria Sharapova in the opening round.
The 23-year-old, who is ranked 30 in the world, will now be hoping for victory over Serbia's Jelena Janokvic or France's Arvanne Rezai on Saturday, to progress to her second WTA Tour final of the year.