Fernando Badillo scored 14 points with four rebounds in its 53-50 win over Caldwell in West Caldwell.
Caldwell (15-6) led 7-4 after the first quarter when Union City (16-8) took the lead after a 20-15 second quarter.
Union City had the edge against Caldwell in the second half, outscoring Caldwell 29-28 to seal the victory.
Emmanuel Pierre-Louis also scored 14 points for Union City. Byron Vanterpool and Ramces Baez each had eight points.
Joe Diorio led Caldwell with 22 points.
