A scoreless game in regulation went to overtime, when South Western's Abby Stevenson won it with an unassisted score in the 85th minute against visiting Susquehannock on Monday.
The Mustangs outshot the Warriors 18-8 and had nine corners to Susquehannock's two en route to the 1-0 triumph.
Warriors' goalie Ashley Stone made 17 saves while South Western keeper Jacey Shipley had eight stops.
OTHER GIRLS' SOCCER
CONESTOGA VALLEY 4, RED LION 1: At Red Lion, the game was tied 1-1 after the first 40 minutes of play, but in the second half the Buckskins scored three answered goals to take control of the game. Taylor Sprenkle scored the lone goal for the Lions, while Nicolle Sweitzer picked up the assist.