Saracens recovered from being 9-13 down to beat a spirited Northampton side 29-20 on Saturday, booking a Champions Cup semi-final with Wasps.
The London-based outfit were disappointing in the opening period. Despite Owen Farrell kicking them ahead, Northampton dominated much of the first half and went in front through Ken Pisi's try.
Farrell and Stephen Myler then traded three-pointers as the Midlands side went into the break with a 10-6 lead.
Two further penalties by the Sarries fly-half to one by Myler meant that the Saints had a 13-12 advantage with a quarter of the match remaining.
It therefore set up a tense finale but it was the home side that took command. Chris Ashton, on his second game back from a 10-week suspension, scampered over while Chris Wyles also touched down to send them through to the last-four, where they will take on Dai Young's outfit.
Courtney Lawes did cross the whitewash to garner some consolation for Northampton but a much-changed side were eventually outclassed.
Saracens have been the form team in both the Aviva Premiership and Champions Cup this season, but they were surprisingly lacklustre in the first 40 minutes. In contrast, the visitors were outstanding, controlling territory and forcing Mark McCall's men into some surprising errors.
Jim Mallinder's squad initially failed to capitalise with Myler awry from the tee. That allowed the hosts to build some momentum and, when they were awarded an opportunity to go for goal, Farrell was on target.
With Northampton's fly-half struggling with his kicking, they were forced to move the ball wide. It certainly paid dividends as, following Will Fraser's yellow card for a late hit on Ben Foden, the Saints scored the first try of the evening.
Jamie Elliott had already squandered one chance by spilling the ball over the line, but his back three partner made no mistake a few minutes later when Pisi finished off Christian Day's and Teimana Harrison's excellent work. This time, Myler managed to convert for a 7-3 advantage before Farrell reduced the deficit via a long range effort.
However, the Midlands outfit controlled the rest of the half and deserved the four-point buffer that they attained via the pivot's second penalty.
Saracens looked to respond early in the second period and thought they had taken the lead when Duncan Taylor touched down but, after consultation with the TMO, it was ruled out for Fraser's obstruction.
Northampton were now finding it difficult to dominate quite as much, but the hosts initially failed to truly benefit from the increasing number of errors. They did earn a penalty, one which Farrell converted, but moments later the away side hit back through the boot of Myler.
However, with the pressure increasing and the likes of Billy Vunipola and Brad Barritt continually punching holes, the Saints rearguard was eventually breached, firstly by Farrell's three-pointer and then by Ashton's try.
Despite Northampton's commitment, Sarries' quality was beginning to come to the fore, particularly in the scrum. One such set-piece shove meant that their fly-half could extend their buffer before Wyles put the result beyond doubt when he crossed the whitewash.
The visitors had the final word after Lawes scored in the corner, but Saracens deserved the victory.
Tries: Ashton, Wyles
Con: Farrell 2
Pen: Farrell 5
Tries: K Pisi, Lawes
Con: Myler 2
Pen: Myler 2
Saracens: 15 Alex Goode, 14 Chris Ashton, 13 Duncan Taylor, 12 Brad Barritt, 11 Chris Wyles, 10 Owen Farrell, 9 Richard Wigglesworth, 8 Billy Vunipola, 7 Will Fraser, 6 Jackson Wray, 5 George Kruis, 4 Maro Itoje, 3 Petrus du Plessis, 2 Schalk Brits, 1 Mako Vunipola
Replacements: 16 Jared Saunders, 17 Richard Barrington, 18 Titi Lamositele, 19 Alistair Hargreaves, 20 Michael Rhodes, 21 Neil de Kock, 22 Marcelo Bosch, 23 Ben Ransom
Northampton: 15 Ben Foden (c), 14 Ken Pisi, 13 George Pisi, 12 Luther Burrell, 11 Jamie Elliott, 10 Stephen Myler, 9 Kahn Fotuali’i, 8 Teimana Harrison, 7 Ben Nutley, 6 Courtney Lawes, 5 Christian Day, 4 James Craig, 3 Paul Hill, 2 Mikey Haywood, 1 Alex Waller
Replacements: 16 Reece Marshall, 17 Campese Ma’afu, 18 Gareth Denman, 19 Victor Matfield, 20 Michael Paterson, 21 Tom Kessell, 22 JJ Hanrahan, 23 Harry Mallinder
Referee: Jérôme Garcès (France)
Assistant Referees: Mathieu Raynal (France), Pierre Brousset (France)
TMO: Eric Gauzins (France)