Neptune started well and with Michael Bonaparte getting into early foul trouble guarding Darren Townes, the Neptune American had their opponents in real difficulty.
Leading 23-17 at the end of the quarter, the Cork side then found a resilient defence hard to breach and a late Isaac Westbrooks basket gave Killester a 43-40 interval lead.
In the third quarter Neptune completely faded as Killester played superbly and raced into a 12-point lead entering the fourth quarter.
Coming down the stretch Ciarán Roe dominated the point as Neptune were always playing second fiddle against their better-balanced opponents.
The absence of captain Ger Noonan and Darko Bucan proved costly for Neptune but coach Mark Scannell would not use it as an excuse for a dismal performance.
“As a coach I will put my hands up and admit we did not get it right in our preparations but take nothing away from Killester, they are a very good side,” Scannell said.
Elsewhere, Champions UL Eagles got back to winning ways when easily accounting for winless Moycullen, 73-58.
Leading 43-31 at the interval, the Shannonsiders stayed in control and helped by another impressive 22 points from American Delwan Graham, they were seldom troubled by the westerners.
Templeogue are also in search of their first win and despite home advantage against Belfast Star they went down 75-62.
Paul Dick had another outstanding game for Star when contributing 30 points, as the northerners are gradually becoming a formidable unit.
UCD Marian, narrowly defeated by Killester last week, had little trouble in disposing of Moycullen 82-50 with Tyrone King registering an impressive 23 points.
The top game in the Women’s Premier League saw holders UL Huskies defeat Team Montenotte 75-71 in a pulsating game at the Upper Glanmire Sports complex.
Montenotte got off to a dreadful start and trailed by 15 points after the opening quarter. Gradually, the Cork side picked it up and inspired by the Dwyer sisters, Gráinne and Niamh, reduced the deficit to nine points at the break.
UL were under the cosh in the third quarter with Montenotte scoring baskets at will and reduced the deficit to 53-51 entering the final quarter.
Montenotte did everything to derail the champions but the class of Rachael Clancy (25) eventually saw UL hold out.
Singletons Supervalu Brunell also remain undefeated but Meteors pushed them to the limit before eventually prevailing 59-56.
Killester registered their first win of the season when defeating basement side Liffey Celtics.