The Dubliners led from the start but lost their shape in the 34th minute when Neptune produced a grandstand finish to reduce the deficit from 14 points to the minimum.
However, Killester recovered their composure and late free throws from Eoin Chubb sealed a deserved win.
DCU Saints travelled to Anderstown and came with away with maximum points following their impressive 84-61 win over Belfast Star.
The northerners were being tipped as potential championship winners but find themselves winless after four games.
In a pulsating opening half, Martin Provizors (19) kept Saints in the game and they went in at break commanding a six-point lead 43-37.
In the second half the Belfast side dropped their intensity in defence and with Eoin Darling and Pat Glover finding their shooting range the Saints ran their rivals ragged.
Winning coach David Donnelly was thrilled his side had shown composure when Star threatened to get back in the game.
“This is always a tough venue to win at and I am pleased that my players never lost focus with the job in hand,” David said.
UCC Demons travelled to Limerick for a clash with UL Eagles and ran out comfortable 72-58 winners.
American Shawn Atupem who sat seven minutes in the second quarter showed enough of class to finish with a game high 30 points.
Naturally Demons coach Paul Kelleher was happy with the performance: “We were unlucky to lose to Neptune but I think we showed again this evening when we play the defence we are capable of teams find it hard to break us down,” Paul said.
UCD Marian travelled to winless Moycullen and the Galway side almost ended their drought before going down 67-65.
The students can thank the contribution of Daniel James whose 21 points helped the Dublin side stumble over the finishing line.
The big game in the Women’s SuperLeague saw Team Montenotte host DCU Mercy at the Neptune stadium.
Montenotte have not fired on all cylinders in their opening three games but they kept their best for this clash as they demolished the championship favourites 73-49.
It was a tremendous performance by the Cork side, who had Niamh Dwyer in inspirational form, finishing with a game high 19 points.
UL are also going great guns but they were pushed all the way by Killester before running out 68-60 winners.
Ulster Rockets continued with their impressive form of late when they had a comprehensive 81-30 win over Liffey Celtics.