Army (14-15, 10-8) blew a 10-point lead over the Leopards, getting only one basket in the final 3:20 of the first half and took a 43-39 lead into the break.
Lafayette (10-19, 6-12) refused to fold in the second period, and Seth Hinrichs' jumper with 4:23 remaining got the Leopards to within two points, 74-72, of the Black Knights. Army closed-out making six-of-seven free throws, however the victory was not decided until Henrichs missed a potential game-tying 3-pointer at the buzzer.
Kevin Ferguson added 17 points for Army, who will be the No. 5 seed in the Patriot league Tournament and travel to fourth-seeded Bucknell on Wednesday.
Hinrichs scored 19 points and Dan Trist added 16 for Lafayette, which lost both games to Army this season.