What's ahead: Thursday's four-minute free skate, where Slutskaya has a better track record.
"It's going to be like starting over. Like the short didn't really count. Back to square one," Cohen told reporters after her victory. "Anybody in the top three can win."
The top three also includes Japan's Shizuka Arakawa, the 2004 world champion. Cohen, 21, has a pair of world silvers and won her first national title this year, but her resume is not considered quite as accomplished as her two closest challengers.
"She said to have fun and enjoy it," Hughes said of her big sister, the Associated Press reports. "She just said to have fun with everything and I feel like I went out and had fun. It's great she's been here with my whole family and been so supportive.
"Now that I'm on the ice and she's up in the stands, I know how she feels. Maybe she knows how I feel, too."