Ernie Tippett has assembled a well drilled and organised unit at the Diamonds and for most of the evening it looked as though they would frustrate one of the fancied teams in the Coca Cola League.
But with just 16 minutes left Sabin, who scored five goals in 11 league matches at the end of last season to help the Cobblers reach the play offs, picked up a ball in the edge of the box before turning sharply and curling a right-foot shot just inside Billy Turley's left-hand post.
It took 69 minutes for either side to manage a shot on target, such was the lack of creativity as Northampton's greater posession foundered upon stubborn Diamonds resistance.
Stuart Gray's tame shot from the edge of the box broke the stalemate and within a minute Scott McGleish took a Marc Richards' pass in his stride before firing a low drive which Turley managed to smother. Then the Diamonds goalkeeper reacted smartly to nick the ball from off the feet of Sabin.
With the deadlock broken, Diamonds' heads dropped and the home side could have pressed home their advantage when David Galbraith's free-kick was headed over the crossbar by McGleish. Then in the final minute Richards threw himself at a McGleish cross only for the ball to fly wide.
The first half was a disappointing affair, the only chance of note falling to Richards -but he somehow manage to volley the ball over the cross ar in the 29th minute with the goal at his mercy.
The win gives Colin Calderwood's men maximum points from two matches while Diamonds have still to score a league goal under Tippett, who took charge at Nene Park for the final three games of the last season.