A classic striker pairing can be the smash-and-grab variety of a tall target man and a scuttling support striker at low level, but Mosgiel reversed those roles.
It was the diminutive Morgan Day setting up towering central defender Tom Bekkers to break the deadlock with a leaping side foot volley in the crowded goal area that gave keeper Tom Galloway no chance.
Galloway had been a key feature in Northern's well drilled defence which allowed the home side to string passes around outside the penalty area, but which closed ranks nearer goal.
Keeper Galloway made several brave diving saves, and both Craig Wilkinson and Cam McPhail barely missed a tackle all day.
But in the closed space, Mosgiel knocked the ball around with clever passing that probed and probed until openings were created.
However, a combination of poor finishing and resolute defence threatened a scoreless game. Building in confidence, Northern launched several swift breaks with Dave Henderson wriggling free and showing pace.
With no goals at the break, Mosgiel again opted for patience and passing, and Northern went on to have its best spell, with Henderson turning provider with a dangerous low cross, then Mike Arnold blasting a good chance straight at Mosgiel's Andrew James.
Mosgiel brought on Tim Dunn for Mike Abbott, and started to stretch the opposition with Jordan Swaney, Luke Burgess and Day all pushing forward on to some probing passes from Mike McGarry.
The sustained pressure earned a series of corners and free-kicks which gave Bekkers' height and power a chance to open the scoring.
Then it was Swaney carving through and placating local supporters by drilling in an acute angled late goal for the final result.
In Invercargill, Roslyn-Wakari put together a great effort against Spirit FC to win 5-0 with goals from both the Cunninghams, Mike and Aajay, plus Cameron Fraser, Tom Connor and Mike Still.
At the Caledonian Ground, goals by Josh Groom and Kalechi Osunwa moved University into fifth place with a game in hand by beating bottom side Green Island.
Top team Dunedin Technical travelled to play Queenstown and, despite some resistance and goals by Chris Acott and Grant Alexander, the Dunedin side won 7-2.
Predictably, leading striker Aaron Burgess scored a couple to stretch his tally in the Golden Boot race to 22 goals, nine ahead of closest rival Darren Overton, of Caversham.
Caversham had a 7-1 win over Grants Braes, with goals by Ben Hawkey, Evan Jones (2), Harley Rodeka (2), Patrick Fleming (2).
Braes' scorer was Saad Ali.
