Northampton 23 Leicester 19
A try with just three minutes left on the clock saw Northampton win yet another compelling East Midlands derby, despite playing an hour of it with 14 men.
Jamie Elliott dived over to earn the Aviva Premiership leaders the points from a thrilling encounter which saw the lead change hands on five occasions.
The main talking point came after 17 minutes when Saints skipper Dylan Hartley was sent off for elbowing Matt Smith in the face. It was a clear red and the England man is likely to face a lengthy ban from the game with a rap sheet as long as the M1.
Saints seemed unperturbed by his absence though and three second-half tries by Alex Waller, Ben Foden and Elliott earned them a fully-deserved victory in a game painfully reminiscent of last season's Premiership semi-final.
Saints won the first kickable penalty of the game but chose against going for the posts. Kahn Fotuali'i took a quick tap penalty instead of going for the points and it nearly paid dividends as the home side marched down to the field and only lost the ball two metres short of the line.
As the home fans bayed for blood, Leicester won the scrum against the head and cleared their lines.
Tom Croft then stole a line-out and Ant Allen made a clean line break as Tigers settled well.
Ben Youngs was box-kicking well and when Tigers won a scrum penalty, they had the first chance to open the scoring with the boot only for Williams to pull a 40-metre kick wide of the mark on 13 minutes.
The first-half's big talking point arrived on 17 minutes. As three or four players from both sides grappled in midfield miles away from the play, Saints hooker Dylan Hartley elbowed Matt Smith in the face and was sent off by referee JP Doyle.
Having been sent off in the final between the two teams back in 2013, he is now likely to face a lengthy ban with plenty of previous form on his rap sheet.
Tigers won two penalties at ensuing scrums and, when the Northampton's scrum collapsed for a third time, Doyle went under the posts for a penalty try and Williams made it 7-0.
Saints beat Tigers in last season's semi-final having been reduced to 14 men so it was not a position they were unaccustomed to.
And they were the better side for the remainder of the first half as they enjoyed more possession and looked the more likely to score with ball in hand.
As it was, they had to settle for six points from the boot of Stephen Myler with penalties on 27 and 39 minutes to drag the score back to 7-6.
There was another big moment just before the break as Tom Croft was yellow-carded for a high tackle and it cost Leicester dearly as Saints shot out of the blocks in the second half.
The hosts piled forward in numbers and with Leicester's defence far too passive, Saints made inroads and finally crossed the line with prop Alex Waller on 44 minutes.
With Myler off for a concussion assessment following one of a number of huge number of hits in the game from both sides, James Wilson missed the conversion but his side led 11-7.
Northampton stayed on top and could have stretched the lead had Myler not missed a penalty on 53 minutes.
Leicester were really struggling for momentum against Saints' physicality but on 61 minutes and out of nowhere, they re-took the lead. Substitute Michele Rizzo rampaged through the Saints defence, Freddie Burns continued to make inroads and Niki Goneva ran in for a score.
The conversion was missed though and just three minutes later, Ben Foden had far too much space down the left flank to ghost in untouched for a 16-12 lead.
Saints turned down a kick at goal to go for the corner but their line-out came to nothing and Tigers marched up the other end of the field and scored through Goneva again.
It was the easiest of run-ins for the Fijian but the try was made by Miles Benjamin who bashed his way through three tackles on the right before recycled quick ball saw Goneva in acres of space on the left.
Freddie Burns landed a touchline conversion and Tigers led 19-16 with nine minutes left.
There was still time for a fifth and final lead change and with just three minutes left on the clock, Jamie Elliott found space on the left to crash over and raise the roof of Franklin's Gardens. Myler made the extras to make it 23-19 and Leicester could never get the ball back as Saints ran down the clock for a memorable victory.
For Leicester, the losing bonus point would have been little consolation.
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