Former world number one Venus Williams won through to the Bank of the West Classic final thanks to a straight-sets victory, while Lauren Davis reached her first WTA Tour final in Washington.
Contesting her eighth semi-final in Stanford, Williams saw off fellow American Alison Riske 6-1 7-6 (7-2) on Saturday.
Williams barely raised a sweat in the opening set, converting two break points and not facing one of her own in a straightforward start to proceedings.
The second set was more evenly contested as Riske stepped it up a notch, threatening to force a decider on more than one occasion, but seven-time grand-slam champion Williams refused to be denied an 80th appearance in a WTA final.
Johanna Konta is next up in Sunday's final after the Brit won the battle of the seeds to reach the first WTA final of her career.
Konta was a class above second seed Dominika Cibulkova, triumphing 6-4 6-2 in just over an hour.
A semi-finalist at the Australian Open in January, Konta saved all three break points she faced against the 2013 champion in the opening set as she won 94 per cent of points on her first serve.
Konta only lost two points on serve in the second set to book a showdown with Venus.
Lauren Davis also progressed to her first final after triumphing at the Citi Open in Washington.
The 22-year-old American defeated countrywoman Jessica Pegula, who upstaged top seed Samantha Stosur in the quarters, 6-2 6-3.
Davis will face a step up in class when she meets seventh seed Yanina Wickmayer in the showpiece.
Wickmayer withstood the sweltering conditions in the American capital to see off sixth seed Yulia Putintseva 6-4 6-2 for her first final of the year.