Dominico Lucindo led the Fighting Maroons with 13 points while Sam Paquiz and Julius Raymundo added 12 markers each.
UP, which bounced back from a setback dealt by University of the East in its opening game, pounced on UST’s error-prone output.
The Growling Tigers played hardly looked like the team that went into the Finals last season, as they committed 33 miscues that led to easy points for the Maroons.
Meanwhile, Adamson thwarted Ateneo, 25-16, 25-17, 17-25, 25-16, for its first win of the season.
Ron Jay Galang powered the Falcons with 20 points.
The Blue Eagles absorbed their second straight defeat in as many outings.
The Tigers also slipped to 1-1.