A goal 13 minutes from time from roving defender Cion Samuel sent Naparima College into next week's RBTT InterCol semis.
The lone item at the Manny Ramjohn Stadium in Marabella, yesterday, was headed home from a Sherrick Hilaire pass.
Carapichaima had first crack at goal, captain Kerron Smith finding the side netting in the 22nd minute. And then, eight minutes later, Smith, with goalkeeper Leston Shade at his mercy, kicked overbar from 12 metres out.
Naparima's best opportunity in the first half came in the 44th minute, when Danaka Jimdar's free kick from just outside the 18-metre area was tipped over by 'keeper Earvin John.
Naps coach Kertwyn Baird had Dazel Lara man-mark Smith in the second session of play. The ploy put the Carapichaima skipper out of the game.
The central zone supporters constantly chanted "Green Boys, we want a goal". It was not to be. Naps, on the other hand, came alive, but Samuel's powerful, long-range shot was pushed over by John.
Trailing one-nil, with just two minutes to go in the game, Carapichaima made a rare raid. However, Mycall Bedasie shot straight at Shade from inside the area.
Naps face north zone champs Fatima College in a semi-final duel on Wednesday, one day after east zone teams San Juan and St Augustine do battle for a championship match berth.