During the previous four weeks, Saints had found ways to win.
But on Friday night at Franklin's Gardens, they found a way to lose.
From 16-8 up to 20-16 down, Saints suffered their first Gallagher Premiership home defeat of the season to a London Irish team who had gone into the game on a seven-match losing streak.
It was another shock result in a largely unpredictable Premiership campaign.
And it left a sour taste in the mouth for Saints as they head into a mid-season break.
They are out of the Anglo-Welsh Cup, meaning they will not play again until Bristol Bears come calling at the Gardens on February 16.
And they would have been desperate to take another win with them on their holidays.
Instead, they are left with a long three weeks to contemplate what went wrong in Northampton on Friday night.
And they might need the full amount of time to do that.
Because this was a scratchy Saints performance, which, once again, started sluggishly.
They have been able to overcome a lethargic first half in recent wins against the likes of Benetton and Lyon.
And they looked to have done it again here, only to be denied at the death by two Irish tries in the space of the final seven minutes.
Before that, it looked like Saints had cleared several hurdles that were placed in their way.
They had Piers Francis stretchered off and Api Ratuniyarawa sent off.
Not only that, but they also lost the likes of Ollie Sleightholme and Taqele Naiyaravoro to injury.
And it was the Naiyaravoro moment that was perhaps the key point in the match. Maybe even more crucial than the Ratuniyarawa sending off.
Because when Naiyaravoro was forced off 14 minutes from time, Saints still looked in control.
Irish had struggled to emerge from their own half, even when they had a man more before Nick Phipps was sin-binned.
Saints were fired up, piling the pressure on and winning a penalty that James Grayson dispatched to make it 16-8.
But when Naiyaravoro went off, Cobus Reinach, who had been playing well at scrum-half, had to go on the wing.
It brought a fresh Henry Taylor into the game, and he struggled to get a grip of it.
Irish, buoyed by the fact they no longer had the menacing Naiyaravoro running at them, started to make ground.
The momentum swung and the pressure Irish put on Taylor eventually paid off as Franco van der Merwe scored before Taylor's box kick was charged down, allowing Dave Porecki to seal a memorable away win for Irish.
It was a sobering night for a Saints team who had reacted so well to December disappointments against the likes of Leinster and Sale.
No, Chris Boyd's team never really put a full 80-minute performance together against the likes of Gloucester and Wasps, but they got the job done.
And though Taylor didn't have a good cameo against Irish, his efforts in the late success at Wasps shouldn't be forgotten.
Neither should Saints' season so far, which has earned them second place in the Premiership going into the break, along with a Champions Cup quarter-final at Exeter Chiefs.
But there is no doubt the defeat to Irish is a big blow.
It is a match they would expect to win nine times out of 10.
But due to their own decision making, they lost it.
Referee Tom Foley took most of the blame from the fans at Franklin's Gardens, but he merely applied the letter of the law.
The problem is the law, and the utter lack of consistency in the game.
Ben Meehan's ugly off-the-ball tip tackle on Reinach during the first half saw the Saints scrum-half land on his back.
The law says that is a yellow card.
But with that much intent to do damage to an opponent in what appeared to be an unprovoked incident, it should not matter if he landed on his back or his head.
And there is a suggestion that one of the only reasons he didn't hit his head is that the post was behind him.
As for the Ratuniyarawa incident, there have been far worse this season already, notably in a recent Champions Cup game between Glasgow and Exeter, when Warriors player Callum Gibbins was only yellow carded.
And speaking of a lack of consistency, and to add some balance to show there is no Saints bias here, on another day, Reinach's try-saving tackle on Ollie Hassell-Collins could have been viewed differently.
Naiyaravoro was yellow carded for a similar incident against Wasps in September and a penalty try was awarded.
It is the complete absence of consistency that leaves the paying public so bamboozled, and it proved costly for Saints on Friday night.
The next few weeks will be key in their campaign as they simply have to come back stronger when they square up to Bristol, Exeter and Saracens during a hugely testing February.
They may get a couple of players back from England duty, but if they don't, they will have to find ways to summon more of a spark without them.
Because, no disrespect to Irish, who defended superbly on Friday night, far tougher tests are to come.
And Saints now need to get back into the kind of winning habit they had built before the only 100 per cent home record left in the league crumbled on a forgettable Friday night.
How they rated...
Showed some fancy footwork to keep Irish on their toes, but they didn't let him get into dangerous areas of the field... 6
Suffered a head injury just before the break, cutting short his night after a scrappy first half for his team... 5.5
Tried to use his creativity to find ways through the Irish defence, but they shut him down well to stop his threat... 6
The centre, who led the team out on his 50th Saints appearance, simply has no luck and he was forced off with concussion after just 13 minutes
Made a huge amount of carries and metres yet again, and his departure 14 minutes from time due to injury really cost Saints... 7
Not an easy night for the fly-half, who struggled to get anything to click ball in hand and who missed some kicks he'd expect to make from the tee... 5
The scrum-half showed his class once again with yet another score and a try-saving tackle that looked like it might win Saints the match... 7
Threw himself into collisions with real fervour and looked hungry for action having enjoyed few outings this season... 6.5
Saints' lineout struggles returned as Irish enjoyed some easy possession, but this man didn't do too much wrong in open play... 5.5
Got through plenty of work, making 12 tackles without missing one and also carrying hard into traffic but gave away a couple of penalties... 6
Was a strong presence for Saints, with his carrying ability causing some problems as he showed his potential... 7
Was shown a red card with 30 minutes to go and cut a frustrated figure as he left the field before Saints lost it late on... 4.5
Was full of desire, putting in a big shift as he tried to take the fight to Irish, also making 15 tackles without missing one... 7
Refuses to give up, pouring a huge amount of energy into the full 80 minutes and he was unfortunate to be on the losing team... 7
London Irish stopped him in his tracks on a few occasions, holding him up to prevent Saints working off their No.8, and he was eventually replaced... 5
Replacements (who played more than 20 minutes)
ANDY SYMONS (for Francis 13)
Was a big option for Saints as they tried to blast their way through the Irish defence, and he caught the eye on a few occasions in attack... 6.5
TOM COLLINS (for Sleightholme 39)
Was eager to get involved after a couple of weeks out due to suspension, but Irish stopped him having any say in the game... 5
LEWIS BEAN (for Eadie 50)
Wasn't an easy time to come on as Saints went down to 14 men and the lock wasn't quite able to stop Irish getting to Henry Taylor late on... 5
ALEX WALLER (for B Franks 57)
Tried to help a fired-up Saints get over the line, but Irish stood up to the physicality and eventually got their reward... 5
EHREN PAINTER (for O Franks 57)
Hasn't played that much of late and wasn't able to have the kind of impact he would have wanted, missing a couple of tackles... 5
CHRON STAR MAN - Dave Porecki (London Irish)