Amherst took control in the final four minutes for a 57-51 victory over Osseo-Fairchild in the other semifinal.
Kate Glodowski scored 18 points to lead Amherst, which trailed by as many as 10 points in the first half, but managed to improve its record to 24-2.
Osseo-Fairchild was led by Hailey Hart's 14 points as it lost for the first time in 15 games and dropped to 24-2.
Paige Selbo added 12 points and Jenna Pitt 11 for Amherst, while Laura Olson had 10 for Osseo-Fairchild.
Amherst will meet Cuba City, which defeated Oostburg 51-42 today, for the Division Three championship Saturday evening.