The Northerners snared one more set than the Opals in the clash, but were able to build a solid games lead across the fixture to eventually snare the 5-45 to 4-37 result.
Georgie Moore and Wendy Sidebottom - as well as Dale Baldi and Helen Jackson - combined superbly for 6-1 victories in their respective doubles battles to lead the way for the Northerners.
Opal was best served by Justin Hunter and Heather Thomson in a 6-2 result.
McEwen Reserve White, Lemnos and Old Students were the other winners in the top tier during round six, with the results serving to put the squeeze on in the middle of the ladder.
Central Park still holds sway in third spot, but is only two points ahead of Old Students and four in front of White as the season approaches its halfway point.
St Andrews was on fire in the A2-A3-A4 division, defeating Old Students 8-51 to 1-29.
Kieran Moon and Wil Chong stood tall for the Students in the side's only set win, with the likes of Anneleise Benford, Julie Cross, Scott Lucas, Arthur Trinder, Carmel Wileman and Jim Surkitt impressing for the victors.
Percentage remains the only thing separating St Andrews and top side Shepparton North Red following the latter's 7-44 to 2-28 triumph against Central Park.
McEwen Reserve Green, Karramomus, Bunbartha and Undera White also advanced their credentials this campaign by snaring points at the weekend.