Northampton 0-2 Morecambe
First-half goals from Morcambe's Phil Jevons and Laurence Wilson secured victory over Northampton.
The visitors went ahead when Jevons volleyed in Gary McDonald's cross after an error by Byron Webster.
Wilson doubled the lead from the penalty spot when Paul Turnbull needlessly handled in the box from Izak Reid's cross.
Northampton went close through a John Johnson header, but could not prevent a fourth successive defeat.
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Northampton Town manager Gary Johnson told BBC Radio Northampton:
"We all know in football you can be as low as a snake's belly one minute and then as high as a kite the next but it will take a hell of a turnaround that's for sure and we'll have to see whether we have got it in us.
"We didn't show the ability, the aggression or the passion to go and win that game.
"It was a poor show all round."