Northampton plunged Leicester further into Gallagher Premiership trouble with a 29-15 derby victory at Welford Road.
The visitors were clinical when it mattered most as they scored three first-half tries through Cobus Reinach and a Tom Collins brace.
Leicester had Mike Williams and Dan Cole yellow-carded in either period as a poor display left them in relegation danger.
Dan Biggar kicked 14 points for Saints while the Tigers' tries came from George Ford and Tom Youngs.
Leicester captain Youngs overthrew an early line-out in what was a poor home start and the Tigers were soon behind.
The Leicester crowd screamed for a knock-on from Taqele Naiyaravoro and a forward pass, but neither were given by referee Wayne Barnes and it prompted a Northampton try.
Ahsee Tuala's pass found Collins, who led the Leicester defence a merry dance as he raced clear and found Reinach running a trademark support line for his 10th Premiership try this season.
Biggar's touchline conversion effort went narrowly wide and Leicester responded as Youngs steamed through a gap and only a double tackle from Reinach and Biggar stopped Sam Aspland-Robinson from scoring in the corner. Ford did kick a penalty to narrow the home deficit to two points.
Still, Leicester had little to show for their possession and they turned around behind and a man light.
Reinach did brilliantly to steal a turnover and then as he attempted to play, Williams played the ball on the floor and was yellow-carded.
Biggar kicked the penalty and then another neat move from the Northampton back division saw Rory Hutchinson and Collins combine on the right touchline with the latter the scorer.
Biggar converted and soon Collins had his second as a dangerous Northampton outfit took total control with Hutchinson passing to Naiyaravoro who popped the ball up to his fellow wing.
It meant Leicester went into the break 20-3 down.
Biggar extended the Northampton advantage at the start of the second half with a penalty and he then followed it with two more kicks after Barnes yellow-carded Leicester's Cole for going off his feet.
That ended the game as a contest with Leicester never looking capable of a comeback.
Biggar had a try ruled out for a forward pass, but by then the damage had been done as both teams unloaded their benches.
Northampton switched off in the final 15 minutes with the game won.
Ford darted over and converted his own score but it failed to mask another inadequate night at the office for the Tigers.
Northampton missed out on a bonus point and, when Jamie Gibson was sin-binned in the final few minutes, Youngs grabbed Leicester's second.