Mike Ellery’s try sparked a second-half comeback as Saracens booked their place in the LV= Cup final and denied Northampton Saints a shot at silverware in front of Franklin’s Gardens.
Saints were much the stronger in the first half, Sam Olver scoring 13 points though a David Strettle converted try kept the home side in touch.
Ellery’s break and finish woke up Saracens and Ben Spencer struck the match-winning blows with three penalties.
Replacement Lee Dickson’s score made for a tense finale but Nils Mordt gave Sarries breathing space at the end with a drop-goal, securing their first LV= Cup final appearance.
The carrot on the stick for Northampton was not only the chance to avenge their LV= Cup final defeat last year but compete for the trophy at home.
Saracens, however, had their own score to settle after losing out at the semi-final stage to the Saints last year – though it was the visitors who started the strongest.
Olver nearly set away Tom Stephenson before the fly-half, who saw an early drop-goal attempt sail wide, nudged the first three points onto the board with a sweetly-struck penalty.
The always dangerous Kahn Fotuali’i then broke the Sarries line with a sniping run but again a chance was wasted as Jamie Elliott couldn’t quite hold on to an Olver pass.
With 17 minutes on the clock however Saints forced another penalty after Sarries were pinged for not releasing, and Olver duly obliged.
Straight from the restart Tom Collins nearly conjured up some individual magic with a kick-and-chase before the TMO was consulted and pictures clearly showed that the winger hadn’t dotted down.
But that was to be Saracens’ wake-up call and after Hayden Smith stole line-out ball, Marcelo Bosch battered his way across the gain-line to create some space.
And a patient move was finished off with aplomb by Strettle in the 22nd minute, scything through with a diagonal angle that beat the Saints defence all ends up.
Spencer’s conversion attempt was no good and Saints’ half-backs took no time at all to respond.
Samu Manoa and Phil Dowson, who will both wave goodbye to Saints this summer, kept Northampton motoring into opposition territory before Fotuali’i sprung Olver with a short ball.
The 20-year-old weaved past Ben Ransom to finish and then added the extras to hand Saints a deserved eight-point advantage on the balance of play.
Sarries finished the half with a flourish and ever so nearly a try, starlet lock Maro Itoje thundering up the left-hand side in two separate breaks but touch and brilliant Saints recovery denied the hosts both times.
They needed to make up for those missed opportunities and Ellery cashed in on their first of the second half.
In truth it was an effort virtually of all his own making, breaking from midway and crashing over – sidestepping two Saints bodies in the process – while Spencer’s conversion reduced the arrears to one point.
The Wolfpack had their tails up and Northampton indiscipline at the ruck handed Spencer two pops at the posts which he took.
Spencer had found his radar and the game seemed to be slowly slipping away from a complacent Saints, as the scrum-half stepped up again to extend Sarries’ lead to eight.
But with 15 minutes to go and the calm heads of Stephen Myler and Dickson now on the field, Saints gathered momentum and a drive ended with the latter swooping over.
Myler’s conversion cut the points gap to one however in the 71st minute, Mordt kept his cool to nail a drop-goal as Sarries held firm – Nick de Jager notably making a super tackle to bundle a breaking James Wilson into touch.
George Kruis then mopped up a threatening attack in the last play of the game to deny Saints at the death.