The Power Boosters got off to a torrid start, carried a 36-25 lead at the half and hung tough the rest of the way as they cut the Paintmasters lead to two games-to-one in the best-of-seven title playoff.
It was Sharks first win over Welcoat in a finals matchup, and the Power Boosters vowed to make a followup tomorrow to even things up.
The Paintmasters went out seeking a 13th straight win in a final series. Their streak of 12 consecutive victories in the finals included a four-game sweep of the Power Boosters in the first conference.
"I was aware Welcoat was aiming for a 13th straight win. Pero malas sila dahil 13 is my lucky number," said Shark coach Leo Austria.
Austria later commended his boys whom he said came out determined to make a statement after losing the series first two games then losing the major individual honors to their Welcoat rivals in the awards rites Monday.
Shark aces Roger Yap, Rysal Castro, Topek Robinson, Gilbert Malabanan and Chester Tolomia all dished out sterling performances as the Power Boosters dominated a badly stunned Welcoat side.
Malabanan and Robinson fuelled a 14-0 start which the Power Boosters sustained until the end to the delight of their cheering fans in the venue.
Earlier, Montana Pawnshop captured third-place honors following a 72-64 win over Blu Sun Power in a fight-marred game.
Montanas Gilbert Lao and Blus Edwin Bacani figured in a fight and were thrown out of the game. Both are expected to draw stiff sanction from the Commissioner's Office.
Castro proved to be Sharks surprise package as he held his ground against Yancy de Ocampo and went on to deliver the killer blows on Welcoat by pouring in eight of his 13 points in the final quarter.
Yap scored 15 to pace the Power Boosters who drew nine points each from Robinson, Malabanan and Tolomia.