Castro, MVP runner-up in the last two conferences, struck with 17 points including 11 in the third quarter, helping fuel a run that carried the Teeth Sparklers to their fourth win in as many games.
"Hes just showing that he could contend for the MVP award," said Hapee coach Jun Noel of the six-foot Castro, who also logged eight rebounds, four steals and one block against six turnovers.
Poor free-throw shooting that saw the Sparks muff 16 of 34 charities compounded Toyota Otis woes as it absorbed a second straight defeat after a shock win over TeleTech in its first outing.
Inspired by team owner Cecilio Pedro who made his first appearance in a game this season, the Teeth Sparklers unravelled a decisive attack in the third and kept the Sparks at bay the rest of the way.
Earlier, Magnolia Ice Cream got a huge lift from Yousif Aljamal as it slammed Kettle Korn, 97-74, to barge into the win column after dropping its first two games.
Aljamal, the MVP winner in the recent San Beda-PCU NCAA title duel, scattered 23 points his largest output in the PBL thus far.
The Corn Poppers suffered a fourth straight defeat while missing the services of coach Pido Jarencio who sat on the San Miguel bench in the PBA over at the Olivares Gym in Parañaque.
Magnolia coach Koy Banal left midway in the third quarter to also attend his coaching job in the pros. But the Spinners worked well under assistant coach Potit de Vera.