USC handed Illinois State its first home loss of the season, jumping to a 16-1 lead and earning a championship game meeting with Toledo. The title game will be played Saturday in Toledo.
The Women of Troy improved to 24-12, with Gemelos scoring 11 points in the first half. USC held Illinois State to 26 percent shooting.
Ashley Corral had 14 points for USC and Briana Gilbreath scored 11.
Northern Illinois (24-11) got nine points from Emily Hanley.
USC has won four straight road games to reach the tournament finals.