Nabong will miss the early part of the season-ending conference as he continues to recover from off-season surgery to remove bone spurs in his feet.
Coach Ariel Vanguardia said the 33-year-old Fil-Am may not be available for the Bossing until January.
“By mid-December pa siya makaka-full practice,” said the Blackwater mentor.
Semerad, 30, on the other hand, is out for the entire conference due to a patellar tendon injury in his left knee. The 6-foot-4 forward-center has just undergone surgery, according to Vanguardia.
“He’s six months out,” he said.
Vanguardia added he hasn’t seen Semerad since his exit interview shortly upon his assumption of the Blackwater coaching job from Nash Racela.
There were unconfirmed reports about David and twin Anthony dealing with other issues, but the Blackwater coach didn't touch on it.
Anthony Semerad was listed in NLEX's active lineup in a conference where players are required full vaccinations to be able to play.
With two of their big men injured, the Bossings will have to rely on young big men Barkley Ebona, Will McAloney, and rookie Andre Paras to man their frontcourt along with import Jaylen Bond.
Both Ebona and McAloney were acquired in a separate trade with Alaska and NLEX in exchange for Mike Tolomia and Marion Magat, respectively.
Blackwater opens its campaign on Thursday against Rain or Shine in the 6 p.m. main game at the Ynares Sports Arena in Pasig.