Lehigh earned a split with Army in their Patriot League semifinal double-header on Saturday afternoon.
The third-seeded Mountain Hawks took game 1, 6-0, but the second-seeded Black Knights evened things up with a 3-2 victory in game 2.
The decisive game 3 will be played at 1:00 Sunday at West Point.
Lehigh is in the postseason for the first time since 2010.
In Washington D.C., the Penn State-Berks baseball team advanced to the NEAC championship game with a 3-2 win over Gallaudet in 11 innings.
They play SUNYIT on Sunday morning.
The PSU-Berks softball team was eliminated from NCAA tournament play following a 15-10 loss to Manhattanville at Salisbury on Saturday.