Kai scored a minute after entering the game, while Francielle's game-winning goal came in the 84th minute was the first goal her her WPS career.
"Tash has been struggling with her shoulders and I thought a good 45 from her would be better than a soft 90 especially with the heat and the 4 o'clock game," Rampone said. "Fran has been doing an exceptional job at practice. She defends well and I thought that she could sit in front of us and change the point with simple passes. She was a key player for us tonight."
Francielle -- acquired from Saint Louis along with Kerri Hanks, who started in place of Kai, in a midseason trade -- had only appeared in one game with Sky Blue FC.
"I've been working hard all season and I was very excited to get into the game," the Brazilian said. "I wanted to prove to the coaches that I can be on the field with all these other players."
The 92-degree heat slowed down the high-scoring Freedom, which had beaten Sky Blue, 3-1, a week earlier.
Sky Blue FC finished with a 24-12 edge in shots -- 14-5 in the first half.
The only goal Washington scored came in 78th minute off a rebound by Lisa De Vanna after Sky Blue FC keeper Jenni Branam had collided with Abby Wambach on a through ball in the box.
Branam's biggest save of the game came earlier in the second half when she tipped a blast by Ali Krieger off the crossbar.
Sky Blue FC faces Saint Louis Athletica Wednesday in the Super Semifinal at the Anheuser-Busch Soccer Park in Fenton, Mo. (TV: Fox Soccer Channel, live, 7 p.m. ET. )
Aug. 15 in Boyds, Md.
Washington 1 FC Sky Blue 2. Goals: De Vanna 78; Kai (White) 55, Francielle 84.
Washington - McLeod, Senty, Whitehill, Sauerbrunn, Krieger, Lindsey (Huffman, 73), Gilbeau (Singer, 46), Sawa, Moros (Long, 59), De Vanna, Wambach.
Sky Blue FC - Branam, Buczkowski, Dowling, Schnur, Rampone, Averbuch, McCallum (Francielle, 61), O'Reilly, White (Parker, 71), Rosana, Hanks (Kai, 54).
Referee: Daniel Fitzgerald.