Senior guard Jerom Lastimosa knocked down a three-pointer with 5.5 seconds left to push the Soaring Falcons ahead by one.
NU’s Steve Nash Enriquez missed his three-point attempt at the buzzer.
Adamson improved to 7-6 and put pressure on La Salle (6-6) in the race for the No. 4 spot.
Congolese big man Lenda Douanga had 16 points and six boards as he carried Adamson's huge 13-2 third quarter finishing kick for a 53-48 lead entering the payoff period.
Lastimosa had seven points, five rebounds, two assists, a steal, and a block in 27 minutes for the Soaring Falcons.
"He made the most important shot of the game," said coach Nash Racela of his lead guard. "Every game to us is a do-or-die game. That's the mentality that we have going into every game. Kailangan manalo, manalo, manalo, to stay alive. That's the challenge."
Didat Hanapi added nine points on 3-of-6 shooting from distance, while AP Manlapaz got eight in the conquest which was the team's third straight.
NU's loss sent it down to 9-5, already in the Final Four but to force a playoff for the No. 2 spot, its needs Ateneo to lose its last two matches against University of the Philippines and Adamson.
Enriquez led the Bulldogs with 18 points and four boards, while Jake Figueroa had a double-double of 13 points and 11 rebounds in the loss.
NU missed the services of rookie Kean Baclaan who served a one-game suspension after being ejected from the game agianst La Salle on Wednesday.
Adamson 64 - Douanga 16, Hanapi 9, Manlapaz 8, Lastimosa 7, Yerro 4, Sabandal 4, Fuentebella 3, Jaymalin 3, Colonia 2, Barcelona 2, Manzano 2, Barasi 2, V. Magbuhos 2, Flowers 0, Torres 0.
NU 63 - Enriquez 18, Figueroa 13, John 10, Malonzo 7, Clemente 5, Tibayan 4, Yu 2, Palacielo 2, Manansala 1, Galinato 1, Minerva 0, Mahinay 0, Tulabut 0.
Quarterscores: 18-14; 33-36; 53-48; 64-63.