Matt Tubbs scored the only goal of the game as Crawley made it four straight wins with victory at Northampton.
Michael Jacobs twice tested Crawley keeper Scott Shearer before Tubbs netted his eighth of the season with a deflected 10-yard shot.
Home keeper Sam Walker denied Tyrone Barnett a second, while John Akinde and Tubbs both fired over for the visitors.
Jacobs curled a shot against the bar for the hosts, who almost levelled late on when Kelvin Langmead headed wide.
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Northampton Town boss Gary Johnson told BBC Radio Northampton:
"We didn't play well today. Our flair players didn't turn up so that's disappointing and we didn't create enough chances.
"If you had a crystal ball as a manager then you wouldn't play them in the first place but they're good players and they can show things but on the day it wasn't with them.
"If that doesn't happen for your flair players then your team is not going to do enough to win."
Crawley boss Steve Evans told BBC Sussex:
"It was a hard-working performance and we dominated possession for long spells. I think if our quality was a little bit better in the final third we would have killed the game off.
"We restricted Northampton to a shot from distance that hit the bar, but other than that they hardly made a chance.
"Arguably we've been very, very solid. When we've got our big players back and available for selection, we're capable of winning football matches."