Serena Williams remains on course to retaining her Madrid Open title after making light work of Sara Errani in straight sets, 7-5 6-2.
The world No 1 and top seed hit 47 winners on her way to victory over the Italian in one hour and 33 minutes at La Caja Magica.
The defending champion improved to 5-0 against the seventh-ranked Errani and to 30-2 overall this year.
Williams, chasing a fourth title of the year and the 50th of her career, just edged the first set after a skittish start before she broke for the third time in the 12th game.
The American was far more comfortable in the second set as she dominated from the start. She sealed the set and the match by breaking the Errani serve twice to move through into Sunday's final.
"I feel that I played solid," said Williams after the match. "In the second set more than the first I made a few less errors, which was something that I needed to do."
Williams will now face a showdown for the number one ranking with French Open champion Maria Sharapova in the final, after the Russian came through her semi-final with Ana Ivanovic.
But the 15-time Grand Slam champion is not looking to relinquish her position any time soon, adding: "Obviously I love being number one. In my heart I feel I'm number one, but also I love to win tournaments.
"So I think if I just win as many tournaments as I can then I'll continue to be number one."