Mission Viejo is 30-0 and one win away from finishing as the No. 1 softball team in the nation.
The Diablos won their Southern Section Division 2 semifinal game on Tuesday, 2-0, over South Hills.
Arizona-bound pitcher Taylor McQuillin struck out 18 batters and allowed one hit.
Mission Viejo will face Yucaipa in the championship game expected to be Friday night at Barber Park in Irvine.