Leicester moved top of the Aviva Premiership after grinding out an unspectacular 16-12 victory over their fierce local rivals at Welford Road.
Tigers could afford for young fly-half George Ford to miss five penalties and still triumph, courtesy of centre Matt Smith's second half try and 11 points by the young number 10.
On another day, Ford's inaccuracy might have proved costly, but Northampton, who were restricted to four Ryan Lamb penalties, lacked the firepower and tactical acumen to punish Leicester.
Saints led 6-3 just before half-time, but Leicester then scored 10 unanswered points - highlighted by Smith's 53rd minute touchdown - and Northampton could find no way back.
Leicester were without six players on England duty ahead of the forthcoming autumn Tests, but scrum-half Ben Youngs and centre Anthony Allen started after being released by red rose boss Stuart Lancaster. Injured England forwards Dylan Hartley and Courtney Lawes highlighted Northampton's list of absentees, but Calum Clark made an immediate return to action in Saints' back-row after completing a 32-week suspension.
Lamb nudged Northampton into a fourth minute lead through an angled penalty, and Saints dominated early territorial exchanges, culminating in Lamb finding his range again for a 6-0 advantage.
In contrast, Tigers' 19-year-old playmaker Ford - starting instead of an unavailable Toby Flood - missed two penalty chances in two minutes, although he did find his range with a third attempt that cut Northampton's lead. Ford then landed an equalising penalty with the final kick of the half, but entertainment value had been a premium as the teams trooped off level at 6-6.
It took Leicester less than two minutes of the second period to go ahead for the first time, with Saints unable to free themselves from trouble just outside their 22. Youngs' slick service from the scrum base gave Tigers time and space, and Smith was worked over cleverly from close range by substitute Vereniki Goneva for a try that Ford converted.
Leicester had visibly increased the tempo, and although Lamb completed his penalty hat-trick shortly afterwards, Tigers looked capable for the first time of taking charge. Ford made it 16-9 in the 53rd minute when Saints hooker Mike Haywood was penalised for a high and late tackle on home skipper Geordan Murphy, which underlined a slow turning of the screw by Leicester.
There was much greater urgency about Leicester than there had been before the break, and with Ford also growing in confidence, Tigers were able to pin their opponents back. Lamb booted a fourth penalty with six minutes left to set a few nerves jangling in the Leicester camp, but they held on to claim the victory their supremacy in key areas deserved, helped when Lamb was sin-binned three minutes from time for barging Allen off the ball.