Matt Tubbs netted his seventh goal of the season as high-flying Crawley made it four wins on the bounce with a 1-0 victory at Northampton.
The Red Devils picked up all three points thanks to Tubbs' first-half winner and, despite having plenty of possession, the Cobblers didn't create enough in the final third to get something from the game.
Northampton started brightly as Jacobs twice tested goalkeeper Scott Shearer, but it was the visitors who broke the deadlock in the 23rd minute.
Andy Drury's free-kick wasn't dealt with by the home defence and when the ball ran free, Tubbs pounced to beat Sam Walker with a deflected shot from 10 yards.
Tyrone Barnett almost doubled the visitors' advantage five minutes before the break, shooting on the turn only to be denied by Walker after Sergio Torres flicked on a cross from David Hunt.
Lewis Young shot tamely at Shearer in the second half but Jacobs went closest when his curling effort came back off the bar in the 73rd minute with Shearer well beaten.
In between, substitute John Akinde shot over after creating a good opening and, late on, Tubbs almost grabbed his second, his dipping shot going just over.
Northampton almost grabbed a point in stoppage time when Kelvin Langmead headed wide at the far post from a Jacobs set-piece.
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