Ateneo and Adamson have secured places in the Final Four.
La Salle is assured of at least a playoff for a semifinal berth, and a loss by FEU or UP would clinch them a berth in the semifinals.
The loss also formally eliminated the Bulldogs as they dropped to 3-9.
Leading by just one, the Green Archers came away with 9-1 run to formally break the game wide open after what was a neck to neck match for much of the game.
Justin Baltazar and Santi Santillan scored on consecutive occasions before rookie Joaqui Manuel came away with a booming triple to give the Green Archers an 82-75 lead with 1:12 remaining.
“Coming to this game, NU is still a strong team, it just so happened na nag-struggle sila sa camapign nila. Alam naman namin kung gaano kaimportante tong laro tonight,” said La Salle coach Louie Gonzalez.
“If we win this we will be in a better spot, but if we lose this we will be on a different spot,” he added.
Santillan led the way for the Green Archers with 18 points and five rebounds, as Aljun Melecio had 13 points, six rebounds and three assists.
Andrei Caracut also finished with 13 points, Justine Baltazar had a double-double of 11 points and 11 rebounds as rookie Manuel finished with his best scoring output in the UAAP with 10 points.
Dave Ildefonso led the way for the Bulldogs anew as he finished with 20 points, while John Lloyd Clemente scored 19 although was limited to just two points in the final two quarters.
La Salle 84 – Santillan 18, Melecio 13, Caracut 13, Baltazar 11, Manuel 10, Dyke 6, Go 6, Bates 4, Serrano 3, Capacio 0, Corteza 0.
NU 77 – Ildefonso D. 20, Clemente 19, Gallego 7, Yu 7, Ildefonso S. 5, Rike 4, Gaye 4, Joson 4, Sinclair 3, Diputado 2, Malonzo 2, Aquino 0, Galinato 0, Morido 0, Salim 0.
Quarterscores: 17-13; 38-40; 65-62; 84-77.