Laquincy Rideau's free throw with eight seconds to play was the difference. Khris Lane missed a 3 just before time expired.
Nelson and Ivey made back-to-back baskets to put Gardner-Webb (8-8, 3-1 Big South) up 55-54 with six minutes left. Ivey added two free throws and Laquincy Rideau's dunk widened the lead to five.
Lotanna Nwogbo hit two free throws for the Lancers, Rideau converted two from the line for the Runnin' Bulldogs, and Darrion Allen hit two free throws for Longwood to make it 61-58.
Nwogbo's dunk with 3:45 left cut the deficit to a point. The teams traded a free throw before Harold McBride's jumper made it 64-61 for Gardner-Webb. Allen's 3 with 2:32 left tied it.
Nelson's layup and Allen's two free throws made it 66-66.
Shaquille Johnson led Longwood (4-12, 0-3) with 19 points.