There was a time when it felt like Saints may never win at Welford Road again.
Now it feels like they may never lose.
Because, for the third time in succession, Saints rocked up at the home of their rivals and emerged victorious.
As they had on their previous two visits, they played some slick stuff at times.
But, even more importantly, they showed similar character when it came to the crunch.
Though the previous two matches were more meaningful - as they both came in the Premiership - this Premiership Rugby Cup success still felt significant.
It felt like these young Saints players had passed another test in their fledgling careers.
When it mattered most, when the heat was really on, the likes of Fraser Dingwall and Rory Hutchinson came up trumps.
Dingwall delivered a huge, timely defensive hit, a fine assist for fellow Academy graduate Tom Collins and a try within the space of a few minutes.
And those acts turned the game.
Hutchinson came on and added class that complemented his centre partner, showing these two youngsters can form the kind of combination fans dream of.
A partnership forged in the club's Academy, and one that has an abundance of potential.
But this was about far more than just two boys who have become men.
It was about the resilience of the squad as a whole and the unflappable belief that has been instilled in each and every player.
Because after seeing their 14-10 half-time lead go up in smoke - Tigers took control as they went 22-14 ahead - it would have been easy for Saints to buckle.
After all, they had lost leads against Wasps and Saracens in previous weeks as their bench failed to fire.
But on this occasion, in a tough environment, they refused to give up.
They kept going and they finally got their rewards as Dingwall's tackling, Hutchinson's work at the breakdown and the forwards' sheer effort, at scrum and lineout time, proved key.
Saints didn't let their winless start to the season creep into their minds.
It was a microcosm of last campaign, when they started slowly and kept going until they eventually got stronger and finished the regular season well.
And that bodes well for next week's tricky trip to Saracens.
Of course, Saints have gone to Allianz Park with momentum before and come away with nothing.
But even if they do again next weekend, you feel confident they could bounce back quickly.
Because that was what they did during the week just gone, proving their pre-match words were far from hollow.
They said they were going to ramp things up at Welford Road - and they did exactly that.
Yes, there were lapses, things that still need to be worked on.
But that is to be expected at the end of a four-match block that has been seen as preparation for when the serious stuff begins.
They were exploited at times by Tigers fly-half Noel Reid, who found gaps in Saints' rearguard, and had Reid kicked better, it could have been a different story.
But those are ifs and buts.
And when it came down to it, when Saints really needed to defend with all they had, they did it.
They finally figured out how to stop Tigers in their tracks at lineout time and closed the gaps that had been there before, shutting the doors through the middle and out wide.
The fact they didn't let Leicester register a single point in the final 28 minutes on Tigers turf was a real feather in the Saints cap.
They will be tasked with doing similarly strong work at Saracens when things really start to get going next Saturday.
The Premiership and Champions Cup games that lie in wait will rightly be what this team is truly judged on.
But for now it is about savouring another sweet derby-day success.
As 'Oh When the Saints' rang out at Welford Road on Saturday it was about reflecting on how this team has turned the tables on Tigers.
A few years ago, the away fans would sing to lift their side after yet another loss at Leicester.
But now they sing to serenade a side that knows how to win at Welford Road - and has started to do it with satisfying regularity.
How they rated...
Was back in the side after six months out and after shaking off a little early rust, he delivered another impressive showing in Saints colours... 7
Was given a difficult day by Jonah Holmes, who was able to score twice for Tigers in the first half... 5
FRASER DINGWALL - CHRON STAR MAN
A huge display from the centre, whose strong and composed work during the second half helped to turn the game in Saints' favour... 8
Just loves the physicality of the game, throwing himself into contact and refusing to give the opposition a yard... 6
Wreaked havoc at times with Tigers struggling to hold on to him, and his offloads were a really productive source for Saints attacks... 7
Kicked really well and also opened things up with some good passing and game management... 7
Did some great work to set up a try for David Ribbans and he has looked a really useful signing so far... 7
FRANCOIS VAN WYK
Carried really well on a couple of occasions as he continues to get up to full match sharpness... 6
Didn't really have any time to make an impact as he was forced off due to concussion after just 11 minutes
Savoured the scrum battle with Tigers at the scene of one of his most important showings in a Saints shirt so far a couple of years ago... 6
Admitted after the game that he could have improved his discipline, but he was so influential when Saints had the ball and he did largely defend well... 8
The lofty lock got stuck in and he looks a player with real talent as he continues to add power to his game... 7
Clearly has plenty of potential and didn't let the east midlands derby environment phase him at all... 7
A really good showing from the South African, who showed just what he can offer to Saints with his work around the field and at the breakdown. Was a total nuisance for Tigers... 7
Never lets the team down and he was a constant menace again for Tigers here as he kept going and going... 7
Replacements (who played more than 20 minutes)
MICHAEL VAN VUUREN (for Fish 11)
Came into the action earlier than he would have thought but got straight into it and again showed he can offload with some tidy play... 7
TOM COLLINS (for Olowofela 48)
Was part of a set of replacements who made a real difference as he shut down Tigers attacks on Saints' left and finished off a fine breakaway try... 7
BEN FRANKS (for van Wyk 52)
Helped to steady things up front for Saints and his experience was crucial as Saints eventually went from strength to strength... 7
PAUL HILL (for Painter 52)
Looked ready to rumble when he came on and he certainly threw his weight around as Saints seized control... 7
ALEX MOON (for Coles 59)
Helped to earn Saints a crucial lineout penalty and was not shy in the tackle, pushing Tigers back... 7
MITCH EADIE (for Brussow 59)
A decent cameo from the No.8, whose handling and awareness was good as he helped Saints to get a grip of the game... 7
RORY HUTCHINSON (for Symons 59)
A really important 21 minutes from the centre as he not only kept Saints composed with the ball in hand but also chipped in with a big win at the breakdown... 8