Stoughton 35. Union Grove 34
Junior Payton Kahl scored four of her 11 points in overtime as the host Vikings (24-2) held off the Broncos (21-5).
Stoughton rallied back from a four-point halftime deficit to tie the game at the end of regulation.
Junior forward Jenna Rainey scored 11 points to lead Union Grove.
The Vikings will advance to face Onalaska in a Division 2 state semifinal game on Friday at 1:35 p.m.