Top seeded and defending champ Serena Williams destroyed Sorana Cirstea 6-1, 6-2 in one hour on Saturday to reach her second straight final at the WTA hardcourt tournament at Stanford.
The first all-American final on US soil since 2004 will feature top seed Williams against Californian Coco Vandeweghe, a lucky loser from qualifying who defeated fifth seed Yanina Wickmayer 6-2, 3-6, 6-2 to reach the first WTA final of her career.
Vandeweghe got into the main draw after a withdrawal and made the most of her opportunity, beating former world number one Jelena Jankovic in the second round.
Williams had a poor first serve percentage of 37 percent but did not waste time in crushing Cirstea to reach her second final in a week after winning Wimbledon seven days ago.
The Romanian was saddled with 31 unforced errors and got only one break point chance against Williams.
The 30-year-old Williams is poised to join sister Venus on 43 career trophies if she can win another title against her 120th-ranked opponent.
Williams played this week fighting jet-lag after flying over directly from Wimbledon eight time zones away.
"This week was weird," said the 14-time grand slam champion. "I felt like I wasn't there for about half of it, but here it is, Sunday and another final."
Williams finished on her second match point after Cirstea saved a first winning chance a game earlier.
"It took me awhile to figure out her game," Williams said. "I had to wait her out. She hits really hard, but I did well."
Vandeweghe, 21, and coached this week by her mother, will rise to around 75th as a result of her success here, according to the WTA Tour.
She hammered a dozen aces and broke experienced Belgian Wickmayer four times in the match which lasted just over two hours.
At one tense moment Wickmayer drew a warning for swearing.
Vandeweghe said she was furious with herself when she crashed out of qualifying.
"I had a bad tennis day and paid for it," she said. "But once I got into the main draw, I took advantage of my opportunities.
"I stuck with my game plan, I served big and returned well this week. When my game comes together like that I can play well from the baseline.
"I'm just so excited to be in the final."
Vandeweghe's surprise showing this week by far surpassed her previous career bests: quarter-final appearances in her native San Diego and Tokyo two years ago and at Memphis in 2011.
She was the second lucky loser to advance to the WTA semi- finals this season after France's Mathilde Johansson in Fes, Morocco. The last one to reach a final was Hungarian Melinda Czink at Canberra five years ago.