At so many points, it was hard to see Saints losing this.
When the teams were named on Friday afternoon, you felt confident they had enough to end what was at that point a six-game losing streak against their local rivals.
Then, when Nafi Tuitavake flew in for an early try and Franklin's Gardens roared, you felt Saints would use their momentum to put more pressure on Leicester Tigers.
When Ahsee Tuala put them back ahead and Louis Picamoles turned on the power to grab a third try, you felt Jim Mallinder's men had the edge.
And then when Christian Day dived over in the corner, you felt the bonus point had been secured and Saints had grabbed a huge half-time lead.
But it wasn't to be.
Day's try was disallowed and Tigers turned the tide, despite suffering more problems.
They lost fly-half Freddie Burns and flanker Brendon O'Connor to injury at the break, giving Saints what you felt would be another big boost.
But it didn't work out that way.
Instead, the men Leicester brought on for Burns and O'Connor, Owen Williams and Lachlan McCaffrey, emerged as the game's key players.
McCaffrey scored a late try while his team were down to 14 men with fellow replacement Mike Williams in the sin bin.
And Owen Williams displayed nerves of steel to land not only the conversion but two late penalties to provide a vital victory for Tigers, who now sit fourth in the league standings.
Saints had the game in their grasp, especially when Stephen Myler had the chance to put them eight points up with 12 minutes to go.
But, unusually, Myler missed and though he made amends with a penalty to put Saints 31-30 up in the closing stages, Owen Williams had the final say.
It was so tough for Mallinder's men to take.
And the scenes of jubilation in the away camp, as well as the fact Owen Williams was named man of the match for his 40-minute performance, rubbed salt in already sore wounds.
Tigers had done it again. They had won it when it mattered against their old foes.
It's now seven successive east midlands derby victories for Leicester, and don't Saints know it.
In the build-up to games against Leicester, Saints supporters enjoy reliving the glorious victories that came in 2014.
Saints beat Tigers twice during that year, in the May Premiership play-off semi-final and in the December meeting, which was also at the Gardens and was the last time Northampton beat Leicester.
On both of those 2014 occasions, they secured the success despite being down to 14 men, with Salesi Ma'afu sent off in the first game and Dylan Hartley in the second.
But this time it was they who were stung while enjoying a man advantage.
Tigers shrugged off Mike Williams' yellow card and scored that McCaffrey try to get back in the game.
And Saints were once again left to wonder what might have been.
The negatives were obviously the result and the fact Tigers dominated the scrum battle, with referee Greg Garner awarding them penalties aplenty in the forward contest.
It was a real area of strength for the away side, and it showed just how important the set piece battle is in games between teams who are so evenly-matched.
The positives for Saints included their ability to score tries - they have had no trouble with that since the turn of the year - and the reintroduction of their Six Nations stars.
Each international player contributed to the cause, with Louis Picamoles and Courtney Lawes particularly impressive.
But that won't be much consolation for Saints now.
Instead, they will have to attempt to bounce back at Wasps in a couple of weeks' time.
That is a hugely tough ask and, with games against Saracens, Exeter Chiefs and Harlequins to follow that, it doesn't get any easier.
But for now, Saints will have to review derby day.
And when they watch it all again in team meetings, they will continue to scratch their heads about the one that got away.
How they rated...
A sparky showing from the full-back, who was lively throughout and tracked Picamoles well to pick up an offload for Saints' second score... 7
Was in fine form during the international period and he didn't do too badly here in a game when both teams tried to play some running rugby... 6
Has grown into the Saints 13 shirt and he was good in attack again here, grabbing an early score and showing some nice touches... 7
Always looks dangerous in attack and made a couple of breaks to keep the Tigers on their toes, but did have a difficult time in defence on occasion... 6
Had been scoring plenty of tries for Wales in recent weeks, but Saints weren't able to get the ball to him in dangerous positions... 6
Kicked well throughout and his early high ball put Telusa Veainu under pressure that led to Tuitavake's try... 7
The scrum-half had a really good game, looking sharp during his time on the pitch and helping Saints keep the tempo high during the first half... 7
Saints had a tough time in the scrum and it was a big ask for this man up against England ace Dan Cole, though he did put everything he had into his overall display... 5
Was given a warm ovation when he was replaced after putting in a typically abrasive and determined performance... 7
Carried well on a couple of occasions, but did not find favour with referee Garner, with Ellis Genge getting the upper hand in the eyes of the official... 5
Another huge display from the England lock, who continues to impress this season, with his work rate so high... 8
Was unlucky as his foot just went into touch as he dived over for a try, but this was another strong showing... 7
Produced a lovely offload to get Saints going in the first half and was full of energy as he battled hard throughout... 7
Poured everything he had into it as Saints put plenty of pressure on Tigers and the home side's back row was an area of real strength, as expected... 7
LOUIS PICAMOLES - CHRON STAR MAN
It was like the Frenchman had never been away as he produced yet another incredible display that included a try and a superb run and offload for Tuala's score... 8
Replacements (who played more than 20 minutes)
MIKE HAYWOOD (for Hartley 57)
Saints had the luxury of leaving this man on the bench, but the top scorer still got to play his part as he put plenty of energy into the performance as usual... 6