Saracens secured a home Premiership semi-final with a 42-38 win over Northampton at StoneX Stadium.
Owen Farrell scored three penalties to Tommy Freeman's try, with only one point in it at the break.
Nick Tompkins, Alex Lewington and Theo McFarland raced Saracens 28-10 ahead.
McFarland's second and a fifth try from Alex Goode gave Saracens the win, but Rory Hutchinson, Matt Proctor and Tom James' double earned Saints two crucial bonus points.
Gloucester's defeat by Harlequins meant Northampton needed only five points from their final two matches to secure fourth place.
While the win was Saracens' seventh consecutive league victory, Saints' three tries in the final 10 minutes meant they took a losing bonus point and four-try bonus point, to move two points clear of the Cherry and Whites with one round to go.
They face Newcastle at home on 4 June, while Gloucester host Saracens.
Second-placed Saracens put the first points on the board inside two minutes and Saints struggled to get outside their own 22 as England captain Farrell made it 6-0.
But their attack repeatedly fell short as they scored no tries despite seven visits to the Saints 22 in the first half, with Tompkins and Goode both seeing golden chances go begging.
Two yellow cards in two minutes for Alex Coles and captain Lewis Ludlum saw Saints reduced to 13 men. However, the visitors impressively weathered the onslaught and scored three points to Saracens' zero during the period.
It was a different story after the break, as Saracens came out firing to score three tries in nine minutes. Tompkins ran over first, then Farrell set up Lewington and McFarland charged and touched down Alex Mitchell's kick.
Replacement Hutchinson reduced the deficit to 11 points with his first touch of the match. But McFarland spectacularly dived in the corner and Goode collected a perfectly weighted kick-through from Farrell for Saracens' fourth and fifth tries.
With 10 minutes to go, Sarries were 25 points clear, however, Northampton did not concede. Freeman caught a cross-field chip from Biggar to set up James' first, a tally he doubled seven minutes later.
And with the last play of the day Proctor went over in the corner to ensure Saints took a crucial two-point advantage into the final-day contest for the top four.
Saracens director of rugby Mark McCall:
"It's a great group of players and a great effort to get 87 points to get a home semi.
"We were really gutted at how we performed last week. Something was not quite right and maybe we were feeling a little bit pleased with ourselves after a few victories but we certainly got a punch in the face.
"We lacked accuracy in the first half and were disappointed not to score against 13 men, but it didn't bother us as we knew if we cut out the mistakes then the tries would come so everyone was calm at half-time."
Northampton director of rugby Chris Boyd told BBC Radio Northampton:
"We thought we showed quite a bit of grit in the first half to keep it pretty close - I think we were actually ahead at half-time, weren't we?
"Fifteen minutes we just lost our focus and composure and let them come back. We were chasing a bonus point and ultimately got two - if you're trying to get four or five, then two's not bad.
"We didn't talk to the players about it [the Gloucester result], just the game drivers we talked about, the fact that our intention was still to try and get five points and if we couldn't then the bonus point might be crucial for us.
"To end up coming away with a couple, it was good."
Saracens: Goode; Lewington, Daly, Tompkins, Segun; Farrell (capt), Davies; M Vunipola, George, Koch; Itoje, Isiekwe; McFarland, Earl, B Vunipola.
Replacements: Lewis, Adams-Hale, Clarey, Hunter-Hill, Wray, Van Zyl, Lozowski, Taylor.
Northampton Saints: Furbank; Freeman, Proctor, Dingwall, Skosan; Biggar, Mitchell; Iyogun, Haywood, Painter; Coles, Ratuniyarawa; Lawes, Hinkley, Ludlam (capt).
Replacements: Matavesi, Waller, Hill, Moon, Nansen, James, Hutchinson, Francis.
Sin-bin: Alex Coles (23), Lewis Ludlum (25)
Referee: Matthew Carley