Second-half goals from Scott Pollock and Sam Hoskins earned Northampton a 2-0 win as Carlisle’s slump continued with a fourth straight league defeat.
It was a happy return to Brunton Park for former Carlisle manager Keith Curle, who saw his side record a second win in the space of four days.
Neither side could establish much authority in the opening phase of the game although Nathan Thomas twice threatened for Carlisle.
His first effort was parried by David Cornell, with Hallam Hope just failing to get a meaningful header on the rebound. Then Thomas again cut in from the left to hit a powerful drive which was deflected for a corner off Charlie Goode.
Carlisle’s Thomas was one of the few bright sparks in the first half and he went close in the 41st minute with a raking 20-yard shot that Cornell tipped away for a corner at full stretch.
The breakthrough for Northampton came six minutes into the second half when Carlisle were slow to get the ball away and Williams fed Pollock, who hammered a left-footed shot high into the roof of the net which gave Collin no change of saving.
The visitors nearly doubled their lead in the 70th minute when substitute Harry Smith forced Collin to dive full length to deal with an accurate low drive and, in the second minute of stoppage time, Hoskins came bursting through to hammer home Northampton’s second.