A 78th minute try from Marcelo Bosch helped Saracens to claim a 27-25 win over Northampton at Franklin's Gardens on Sunday.
The Saints held the upperhand for large periods and eventually outscored Saracens by three tries to two but the visitors showed why they are the champions as they fought until the end.
The result means Sarries consolidate third place on the table while Northampton's losing bonus point moves them into sixth place and the play-off positions.
Henry Mallinder's first half try helped Saints to a 13-6 lead at half-time, with Dylan Hartley going over within two minutes of the restart.
Ken Pisi extended the lead before a late Chris Ashton try put Saracens back into contention. And Bosch turned the game right around at the end, with Alex Lozowski's conversion putting Saracens into a 27-25 win.
One defeat in six for Saints put them as favourites for this one, with Saracens falling to defeat on their travels in their last three.
And seven minutes was all it took for Stadium MK to get rock, with Mallinder crashing through. Ken Pisi handled a high ball from Stephen Myler before kindly feeding the 12, who went through despite almost being held up on the line. Myler added the two for an early seven point advantage.
It looked like a second try had followed inside the first 15, but the TMO deemed that the hosts hadn't made it over the line after pushing from a line-out.
Nothing was going Saracens way though and they lost Duncan Taylor to a yellow for an infringement, the subsequent Myler kick increasing the gap to double figures.
Lozowski reduced the arrears before half-time with two penalties to get Saracens ticking along, but Myler's kick in between kept the gap at seven at the break.
And Saints lead was stretched after half-time with a second try. Hartley emerged from the rear of the maul and barged through within two minutes of the restart, Mallinder extending the lead up to 20-6.
Lozowski was on hand to cut it down again with a third penalty, and he was at his best to slice the lead further back down to single figures in a promising showing from the 23 year old.
But it was Saints who were more dangerous when it came to the 22, and try three looked to have killed off Saracens. Ahsee Tuala made his way down the wing, with Pisi offering a valuable outlet. And after neat passing, he was on hand to go through.
The visitors continued to push though and Ashton dived over to cut the gap down to eight points with 10 left to play. A quick penalty put them right up on the line, and Ashton was on hand to touch down.
Lozowski added another three to reduce the arrears further, and the game was turned right around with three left to play. Bosch went over after Saracens turned over possession at the breakdown, and Lozowski kicked Saracens into a vital 25-27 lead.
Tries: Mallinder, Hartley, K Pisi
Cons: Myler, Mallinder
Pens: Myler 2
Tries: Ashton, Bosch
Pens: Lowzoski 5
Yellow Card: Taylor
Northampton: 15 Ahsee Tuala, 14 Ken Pisi, 13 Luther Burrell, 12 Harry Mallinder, 11 Ben Foden, 10 Stephen Myler, 9 Nic Groom, 8 Louis Picamoles, 7 Tom Wood (c), 6 Jamie Gibson, 5 David Ribbans, 4 Courtney Lawes, 3 Kieran Brookes, 2 Dylan Hartley, 1 Alex Waller
Replacements: 16 Mikey Haywood, 17 Ethan Waller, 18 Paul Hill, 19 Api Ratuniyarawa, 20 Teimana Harrison, 21 Lee Dickson, 22 Rory Hutchinson, 23 Juan Pablo Estelles
Saracens: 15 Alex Goode, 14 Nathan Earle, 13 Marcelo Bosch, 12 Duncan Taylor, 11 Sean Maitland, 10 Alex Lozowski, 9 Ben Spencer, 8 Jackson Wray, 7 Schalk Burger, 6 Joel Conlon, 5 George Kruis, 4 Nick Isiekwe, 3 Vincent Koch, 2 Jamie George (c), 1 Titi Lamositele
Replacements: 16 Schalk Brits, 17 Hayden Thompson-Stringer, 18 Petrus Du Plessis, 19 Michael Rhodes, 20 Billy Vunipola, 21 Henry Taylor, 22 Nick Tompkins, 23 Chris Ashton
Referee: Matthew Carley
Assistant Referees: Wayne Falla, Gareth Copsey
TMO: Graham Hughes