Saracens survived a late fightback from Northampton to land a psychological blow on their closest Aviva Premiership rivals ahead of the looming play-offs.
The possible dress rehearsal for the Twickenham showpiece on May 31 ended in a tight 28-24 victory for the 2011 champions that extends their lead at the summit of the table to 10 points over second-placed Saints.
David Strettle, Kelly Brown and Marcelo Bosch crossed for tries to celebrate captain Steve Borthwick's record-breaking 263rd Premiership appearance at a sun-drenched Allianz Park.
Bosch, Owen Farrell and Charlie Hodgson weighed in with points from the kicking tee, but the victory came at a cost as Farrell failed to appear after the interval because of a foot injury.
Double-chasing Saracens, who have also secured a place in the Heineken Cup semi-finals, were coasting to victory after easing 28-10 ahead of surprisingly passive opposition who only sprang into life in the final 10 minutes.
Northampton spent last week at a warm-weather training camp in Lanzarote and were woefully off the pace until Luther Burrell and George North crossed within three minutes of each other.
The quickfire tries transformed the closing exchanges but Saints - who won last year's semi-final at the same venue 27-13 - fell just short of turning the bonus point into something more substantial.
Strettle's rich scoring form resumed in the ninth minute when he collected a beautifully-weighted chip through by Farrell and touched down in the left corner for his 15th try of the season.
The promising start from Saracens soon descended into a 10-5 deficit with Stephen Myler landing a penalty and conversion after referee Matthew Carley awarded a penalty try.
The home pack scattered before a Northampton driving maul that started on the 22 and with defenders entering illegally from the side, Carley awarded the score under the posts.
Stung into action, Saracens crossed through Brown in the right corner with Schalk Brits' burst up the middle once again causing chaos in Saints' defence in the build-up.
Brits' outstanding afternoon continued with brilliant successive off-loads from the floor before Allianz Park winced as Courtney Lawes flattened England team-mate Farrell.
Bosch took over the kicking duties and he justified the decision by landing two penalties in quick succession.
Saracens were building up a head of steam with Mako Vunipola scattering defenders and only lightning reflexes from North prevented a try for Chris Ashton.
The first half ended with a Farrell penalty, but the England fly-half's afternoon was soon over, with Charlie Hodgson replacing him during the interval.
Apart from an early burst by the towering North, Saracens' dominance continued unchecked despite making a flurry of substitutions.
Bosch squeezed over after Richard Wigglesworth had weaved a path upfield, with Ashton stopped inches short. The Argentina centre took up the baton and finished the move.
An outstretched arm from Burrell delivered Northampton's second try following a defensive lapse from Strettle and the England centre was involved again to set up a grandstand finish.
He forced his way to the line and offloaded with the ball reaching North via a Saracens hand, and amid a melee of bodies the British and Irish Lion forced his way over in the 76th minute.
Myler converted the try and Northampton pressed again, but Saracens' resolve was evident in the closing stages.