The 5-foot-10 Yu banged in nailed a backbreaking three-pointer that pushed the Kings’ to 73-68 with 34 seconds remaining before a Joseph Brutas’s layup pulled the Slashers to within 70-73, only 17 seconds left.
Nueva Ecija still had a lifeline after San Juan guard Rence Nocum muffed two free throws, but Chris Lagrama missed a triple at the buzzer.
Nocum wound up with 20 points and six rebounds for San Juan, while Yu chipped in 10 points, two rebounds and three assists.
Nikko Panganiban also had 10 points and four reounds for the Kings, who remained unbeaten with a 6-0 card.
The Slashers, coming off a 72-71 escape over the Pampanga G Lanterns last January 14, fell to 3-7.
Boracay, meanwhile, also edged the Pampanga G Lanterns, 84-81, for its third straight win.
Former Philippine Basketball Association star Mac Cardona sizzled with a game-high 26 points, three rebounds and four assists for the Islanders, while Bryan Faundo turned in a double-double of 15 points and 10 rebounds.
Jaymar Gimpayan and Johnsherick Estrada combined for 25 as Boracay scored a big follow up to its 89-82 triumph over Cagayan De Oro-PSP last January 12 and rose to 5-4 for eight place.
Pampanga dropped to 4-2 at sixth spot.
Lawrence Mallari was the lone bright spot for Nueva Ecija with 18 points and three rebounds.
Jap Pambid paced the G Lanterns with 19 points, nine rebounds and three assists, while Kurt Reyson added 13 points.