It was the Tahitians who scored first through Meirii Si Man in the fifth minute but Vanuatu captain Louis Dominique equalised midway through the period with a powerful shot from the right wing.
Junior Malas made it 2-1 for Vanuatu just before the break, slotting the ball through the legs of Atanui Tetihia after a decisive breakaway.
Tahiti pushed for an equaliser in the second period but an outstanding performance from goalkeeper Daniel Mansale, who was captain on the day, kept Vanuatu in front.
At the other end, Nemani Roqara showed off his ball skills midway through the period to wrong-foot the keeper and give Vanuatu a two goal cushion.
But Tahiti forward Mana Faarahia pulled one back, setting up an exciting end to the match.
Vanuatu successfully absorbed the pressure and got one more in before the final whistle as Tahiti sent too many forward. Ben Hungai claiming the last goal to keep him in the running for Golden Boot with seven goals for the week.
Tahiti, who have the bye tomorrow, must settle for six points from their six matches to lie in fifth place. Vanuatu meanwhile could challenge for second or third spot with a big win over Fiji on the final day of matches tomorrow.