Lassiter, who finished with 25 points, tipped in a missed layup by teammate June Mar Fajardo for the game-winning basket as the Beermen completed a remarkable comeback from 15 points in the second quarter to move within a win from booking a return trip to the finals.
Trailing 98-102 after Joe De Vance’s triple with a little over a minute remaining, the Beermen turned to Lassiter who scored on an outback and a couple of free throws to tie the game at 102 with 15 seconds left.
The Gin Kings committed a five-second violation on their inbound play, setting the stage for Lassiter’s heroics.
“Marcio had the presence of mind but we know we got lucky,” said San Miguel coach Leo Austria.
Arwind Santos sent the game to overtime with a triple with 13.4 seconds remaining after another offensive rebound off a Fajardo miss. Held to just nine points in Game 1, Fajardo had game-highs of 33 points and 19 rebounds in 49 minutes of action.
Still missing seven-foot center Greg Slaughter, Gin Kings coach Tim Cone unveiled a trump card in Prince Caperal, who scattered a career-best 26 points on 11-of-18 shooting.
Japeth Aguilar had 28 points, but failed to score in overtime, where the Gin Kings also went scoreless in the final minute.
In Game 2 of the other Final Four duel, NLEX braces for a big Magnolia fightback when it shoots for a 2-0 lead at 7 p.m. on Monday at Mall of Asia Arena in Pasay.
SAN MIGUEL 104—Fajardo 33, Lassiter 25, Cabagnot 13, Ross 13, Santos 11, Ganuelas-Rosser 7, Heruela 2, Pessumal 0, De Ocampo 0, Espinas 0.
BARANGAY GINEBRA 102—Aguilar 28, Caperal 26, Devance 11, Thompson 10, Cruz 10, Tenorio 8, Mercado 7, Mariano 2.
Quarters: 25-30, 42-55, 70-73, 95-95 (reg.), 104-102 (OT)