Regnier defeated Arizona State's Celena McCoury, 6-0, 6-1, to advance to the finals.
In doubles action, Regnier and teammate, freshman Perrine Pernin, were tripped up in their flight two semifinal round match by California's Sekita Grant and Raquel Kops-Jones, 9-7.
Regnier and Pernin cruised into the semifinals after earning a first round bye and a quarterfinal round victory over UCLA's pair of Chelsey Godbey and Mariko Fritz-Krockow, 8-1.
The Wildcats return to action Friday, Jan. 26 as they travel to Los Angeles to open up conference play against UCLA at 2:30 p.m. MST.
Sophie Regnier (UA) def. Celena McCoury (ASU), 6-0, 6-1
Lauren Barnikow (Stanford) def. Regnier (UA), 6-3, 6-3
Perrine Pernin/Regnier (UA) def. Chelsey Godbey/Mariko Fritz-Krockow (UCLA), 8-1
Sekita Grant/Raquel Kops-Jones (California) def. Pernin/Regnier (UA), 9-7