Tied at 1-1 following 90 minutes of regulation and 20 minutes of sudden victory overtime, the two teams were forced to determine an advancing team via penalty kicks.
Shenandoah (14-3-1) converted on four of its five tries from the spot, clinching it when sophomore Jenna Kline buried her attempted into the right side of the net on the Hornets fifth and final attempt.
Kline's conversion gave SU a 4-3 advantage in the PKs as SU keeper Kat Terza stoned both Player of the Year Pernilla Milton and Annika Rindestedt on consecutive attempts.
Hana ElFallah missed wide on her shot before Jenna Ortman converted for Averett (14-3-1) on its fifth attempt, setting Kline up to seal the advancement if she could convert.
The sophomore wasted little time, stepping up and pushing her shot just to the left of AU keeper Samantha Lupo for the clinching goal.
SU scored its only regulation goal at 59:35 on a Cataldo to Brittany Butcher tally before Averett tied it just over eight minutes later.
Cataldo gave the Hornets the lead by finding Butcher just inside the 18-yard box, where the sophomore tucked her shot between Lupo and the right post.
Milton brought the contest back to level by heading a Suvi Piipponen volley past on-rushing Terza.
Milton caught Terza coming off her line and headed the ball just before Terza could make a play on the service.
Averett had the best remaining chance of regulation, but Annika Rindestedt knocked her shot above the crossbar from 12-yards out.
The two teams then played 20 minutes of scoreless soccer before going to the PKs.
Note: Per NCAA rules, this game ends officially as a tie with Shenandoah advancing on the penalty kicks.
1. Sandau - good
2. P. Milton – fails (saved)
3. Rindestedt – fails (saved)
4. Piipponen - good
5. Ortman - good
1. Hensley - good
2. Womack – good.
3. Cataldo - good
4. ElFallah- fails (wide right)
5. Kline – good