Madison Keys roared past top-seeded Wimbledon champion Garbine Muguruza 6-3, 6-2 on Saturday to book an all-American WTA Stanford final against CoCo Vandeweghe.
Keys, the third seed, needed just 57 minutes to subdue Muguruza, who claimed the second Grand Slam title of her career when she beat Venus Williams in the final at Wimbledon.
Keys ended Muguruza's nine-match winning streak, and reached her first final of 2017.
She'll face fellow American CoCo Vandeweghe, who reached the final with a 6-3, 6-1 victory over CiCi Bellis.
Although she was broken early in each set, Keys showed plenty of resolve in breaking back both times. She gained the decisive break in the opening set for a 5-3 lead and served out the set.
She then broke Muguruza as they opened the second set with three straight service breaks, and when Keys then held she had a 3-1 lead.
She broke Muguruza one more time to make it 4-1 when the Spaniard knocked a forehand into the net.
Firing on all cylinders on her own serve, Keys wouldn't face another break point, and finished off the match with a service winner.
"I was really happy with how even though I got broken right off the bat in both sets I held it together and stayed composed," said Keys, who was sidelined at the start of the year by a wrist injury and has struggled to find consistency.
"This whole tournament for me has made me feel so great. This whole year has been kind of rough."
Vandeweghe, seeded sixth, hasn't dropped a set en route to the final.
It was the initial career meeting between the two young Americans and Vandeweghe used her experience to dominate the 65-minute contest.
Vandeweghe, 25, reached the Stanford final in 2012, when she fell to Serena Williams.
"I'm five years older, and hopefully I'm more mature," Vandeweghe said.
"I think (I'm) a little bit of a different tennis player. You grow and evolve as a tennis player and as a person, and I think especially in the last two years, it's been kind of clicking in that regard."
Vandeweghe won eight of the first nine points to set the tone in the opening set. She lost her serve once in the first set, the first time she had been broken all week.
She was the aggressor, hammering seven aces, winning 80 percent of her first serve points and breaking Bellis's serve a total of five times.