Mike Heitzmann's strike helped the Terps walk off the Scarlet Knights with a 5-4 edge in penalties.
Two Terps also made the all-freshman squad.
The Terps start their Big Ten tournament run with a rematch against Rutgers on Saturday afternoon.
Both goalkeepers pulled off a handful of impressive saves throughout Wednesday's match.
The Terps are riding a four-game winning streak into Senior Day.
Lenahan, Northwestern men's soccer's longtime coach, is due to retire at the end of the season.
Goals from Ben Bender and Malcolm Johnston pushed the Terps to their fourth straight win.
The Terps haven't lost since Cirovski shifted from his favored 4-3-3 to a 4-4-2 formation.
Bin grabbed both goals in Maryland's 2-1 win over Michigan State.