Seton Hall seemed in control when Anthony Nelson hit a layup for a 49-42 edge with about a minute to play. Then the Pirates missed three free throws and turned the ball over, setting up Anthony Cowan Jr. to try a tying 3-pointer with 22 seconds left.
Cowan missed, and Seton Hall got the rebound and made a free throw to ice it.
Seton Hall won without Big East Conference preseason player of the year Myles Powell (concussion) and power forward Sando Mamukelashvili (broken wrist).
Cowan led Maryland with 16 points on 3-of-14 shooting. Jalen Smith and Aaron Wiggins added 11 points apiece.
The defense was the difference for Seton Hall, which also got eight points and 12 rebounds from Jared Rhoden.
The Terrapins trailed 27-18 at halftime with their lowest scoring output in a first half this season. Maryland entered averaging 77.1 points per game.
Maryland: The Terps are going to slip in the polls and won’t play again for 10 days.
Seton Hall: The Pirates were coming off losses to Iowa State and Rutgers but got a good win without possibly their two best players. Seton Hall finally beat a ranked foe after near-wins against then-No. 3 Michigan State (lost 76-73) and then-No. 11 Oregon (71-69).
Maryland: Hosts Bryant on Dec. 29 in final nonconference game.
Seton Hall: Hosts Prairie View A&M on Sunday in final tuneup for Big East Conference schedule.