A powerhouse performance from American forward Samu Manoa helped Northampton beat Saracens 20-16 to secure a home LV= Cup semi-final.
Manoa scored two tries and played his part in another for James Wilson as Northampton ensured they will have home advantage against Saracens when the two teams meet again in the final four.
Saracens had gone ahead with 15 minutes to go with Ben Spencer, who scored a first-half try, using his boot to take his personal tally to 16 points.
But it was not enough as Manoa had the final say with an unstoppable score in the corner.
Young Northampton fly-half Will Hooley kicked five crucial points on his debut to help ensure the victory.
Hooley had started the game by missing an early chance to as he fired a penalty wide from in front of the posts.
But Northampton, as they had at Newport a week earlier, were enjoying total dominance in the scrum, laying a platform for the backs.
And, after some nice interplay between Kahn Fotuali'i, Jamie Elliott and Manoa, the ball was worked wide to Wilson, who capped an impressive start by jinking inside to score.
Hooley settled the nerves with a well-struck conversion to take his team's tally to 7-0 before Spencer got Saracens on the board with a penalty won at the scrum.
Northampton were leaking penalties, and they were a man down seven minutes before the break as Samoan scrum-half Fotuali'i was sin-binned for a deliberate knock-on.
Saracens quickly made their hosts pay as Saints were pushed off the ball and Spencer found his way over the try line.
The number nine also added the extras to put his side three points up at the break and the second half started in sluggish fashion.
But Northampton were the first to find the inspiration the game needed, with Manoa smashing his way over the line to finish off a slick move down the left.
Hooley missed the conversion, but kept his nerve to bisect the posts with a penalty soon after as Northampton edged five points in front.
Spencer immediately cancelled out that effort, though, and he soon took his team into the lead with a penalty won by the experience of replacement Jacques Burger.
But Manoa showed desire and determination as he dragged his team back in front with an unstoppable surge over the line.
Replacement fly-half Stephen Myler misfired with the conversion and Fotuali'i did the same with a drop-goal attempt soon after.
But it was not to matter as Northampton closed the game out to set up a tie against Saracens at Franklin's Gardens on the second weekend of March with both sides progressing as winners of their respective pools.