The Nittany Lions seemed to find an equalizer in the 88th minute before a last-second free kick goal from the Trojans.
Jess Mruzik notched 18 kills and Izzy Starck had 46 assists in the win.
Ella Jennes scored the game-winning goal in overtime.
The Nittany Lions stayed put after a bye while the rest of the top five saw plenty of movement.