Shane Drahm's three penalties and a late try from Andrew Blowers settled a rugged East Midlands derby in Northampton's favour at Franklin's Gardens.
Australian fly-half Drahm is likely to find his custody of the number 10 shirt over when Paul Grayson returns from England duty.
But he bowed out in the best possible fashion by stroking over three of his four shots at goal to secure a victory earned by a rugged forward display and his no-nonsense kicking out of hand on a pitch soaked by 12 hours of rain.
So the first half of an old-fashioned east midlands derby full of needle would have delighted him – and the sight of Neil Back and Blowers scrapping on the floor emphasised just how much the game means to these sides.
Leicester dominated the opening quarter with wing Freddie Tuilagli twice going close on the left and Ramiro Pez firing wide with an early penalty shot.
World Cup winner Matt Dawson directed the Saints' resistance from the base of the scrum with a string of half-breaks and clever kicks before limping off with a calf injury in the 27th minute.
His departure, though, turned out to be the cue for Northampton to step up a gear with Drahm opening the scoring with a penalty after Leicester had killed a midfield ruck on their own 22.
Glenn Gelderbloom's chip created another Leicester opportunity for Tuilagi down the left but despite dominating at the set-pieces they could not find a way through before the break.
Drahm made them pay at the start of the second half, adding penalties in the 47th and 59th minutes – the second when England captain Martin Johnson was singled out as the man responsible for killing the ball.
The fly-half missed from the touchline with a 68th-minute effort that would have made the game safe.
But his side controlled the remainder of the match, raining high kicks on the visitors' back three as the errors crept into Leicester's game.
The Tigers could not find a way out of their own half and were punished in the final minute when replacement scrum-half Mark Robinson broke down the blindside with Blowers following up to force his way over in the corner.
For Northampton:Try: BlowersPens: Drahm 3