Leicester Tigers director of rugby Richard Cockerill gave huge credit to young fly-half Owen Williams after winning at Franklin's Gardens.
Williams kicked 17 points, including five penalties, as Leicester took their winning run in the Premiership to nine matches and drew within seven points of Northampton in the league.
Williams joined the English champions this season from the Scarlets, with many believing he should be selected by Wales to tour South Africa later this year.
Anthony Allen scored the only try for the visitors in a typically feisty East Midlands derby, with Leicester losing both Ben Youngs and Niki Goneva to the bin.
"It's a good win for us. I thought we played some really good stuff. By and large, we controlled the game really well," said Cockerill.
"The set-piece was good, Owen Williams' goalkicking was outstanding, and to beat them (Northampton) here on their own patch - the first time they have lost at home in the league this season - it is a very good result for us.
"Owen has been good for us. I thought he was really good today. He ran himself to a standstill. He coped with it really well, and those kicks under pressure were fantastic."
Leicester still remain two wins away from the top two spots in the Premiership, making an away semi-final likely should they qualify for the playoffs.
The prospect of playing on the road however, with Leicester hitting form as ever in March, isn't one that concerns Cockerill.
"The key for us is to be on good form going into a semi-final," added Cockerill.
"At this point, we will be going to Saints or Saracens for a semi-final. We would like to think we can go anywhere and win."