Garbine Muguruza took control early, lost the momentum and then held on at the end to beat Agnieszka Radwanska and reach her first Grand Slam final.
The 21-year-old Muguruza lost six games in a row in one stretch but regrouped to defeat Radwanska 6-2, 3-6, 6-3 on Thursday, becoming the first Spanish woman to advance to the Wimbledon final since Arantxa Sanchez Vicario in 1996.
Muguruza dropped face-first onto the grass after hitting a swinging forehand volley for a winner on match point.
On the previous point, Radwanska held up her racket in the middle of the point to challenge a shot from Muguruza that landed near the baseline. The video replay showed the ball had caught the back of the line, giving the point to the Spaniard.
The second semifinal pitted five-time champion Serena Williams against 2004 winner Maria Sharapova. Williams, who has won 26 straight Grand Slam matches, is chasing her fourth straight major title. She also is bidding for the third leg of a calendar-year Grand Slam, a feat last accomplished by Steffi Graf in 1988.