Saracens boss Mark McCall admitted the manner in which his side lost to Saints was 'horrible'.
The hosts conceded a penalty with just 90 seconds remaining, allowing James Grayson to step up and seal Saints' first win at Allianz Park since March 2016.
Saracens had seemed set to secure the spoils once again when Ben Spencer's penalty, his sixth of the match, put them 25-24 up.
But Grayson had the final say to ensure Saints would win 27-25 and end their run of six successive league defeats to champions Saracens on Gallagher Premiership opening day.
And McCall said: "It's horrible to lose games like that, when it's the last minute that you lose.
"We were in a tough situation just before half-time when they scored two tries and we were under a lot of pressure after the break on our goal line.
"We found a way to tough it out and get into the game, which was very pleasing with a young side.
"We showed resilience out there and we were two minutes away from an altogether different feeling.
"Our effort was good, our ability to bounce back from setbacks was good and those are the things we can take forward.
"There were a couple of things in the last 10 minutes: we spilled the ball and made some mistakes, as well as obviously giving away the penalty at the end.
"It doesn't feel great but we'll look at the game and see what we can improve for next week."