Northampton boss Jim Mallinder accepted that the game is pretty much up for Saints' Aviva Premiership play-off hopes this season after they lost 30-24 against east midlands rivals Leicester.
While Leicester moved to within touching distance of the Premiership play-offs, it left Northampton's hopes hanging by a thread.
Tigers' triumph means they could confirm a play-off place by beating Welford Road visitors Worcester on April 30 after tries from hooker Harry Thacker, wing Vereniki Goneva, and Freddie Burns underpinned victory.
Fly-half Burns added three penalties and three conversions for a 20-point haul, with Tigers' victory also nudging Exeter closer to the play-offs alongside confirmed qualifiers Saracens and Wasps.
If Leicester see off the Warriors later this month - or win their final regular season fixture at Bath seven days later - then Saints will be resigned to a fifth-placed finish at best, whatever they do in their remaining matches, although a top-six outcome guarantees European Champions Cup qualification for next term.
"I think, realistically, that's the top four out of reach this season," Mallinder said.
"We always keep fighting, but today summed up our season a little bit. We just weren't quite good enough.
"The referee (Tim Wigglesworth) had a poor game today. It was so inconsistent in terms of we didn't quite know what was happening in the scrum.
"When you give away seven or eight penalties for one offence - collapsing our maul - it has got to be a yellow card, and it has got to come earlier. They should have been down to 14 men. We are disappointed in that.
"We have got lots of injuries, but you don't use that as an excuse. You battle on, and what it is is an opportunity for other players."
Saints gave as good as they got for most of an enthralling encounter, with number eight Teimana Harrison and centre George Pisi scoring tries, while fly-half Stephen Myler booted three penalties and a conversion and JJ Hanrahan added a late penalty, but Champions Cup semi-finalists Leicester possessed a composed edge at critical moments.
The Tigers now go into a Champions Cup semi-final against Racing 92 in Nottingham next Sunday, and remain on course for a possible domestic and European double.
Leicester rugby director Richard Cockerill said: "It was a pretty scrappy game, really. We got a good start, then got clawed back, then scored an intercept try. I am just delighted with the win.
"I will have to pick the bones out of the performance, which probably wasn't brilliant from us, but three tries to two, we probably deserved to win the game in the end."
Cockerill also paid tribute to the performances of Thacker and Burns, who delivered outstanding displays.
"Harry is a great footballer, and if he can cope in the scrum, which he is managing to do, his footballing ability is as good as anybody's," Cockerill added.
"Freddie is a confidence player, and Aaron Mauger (Leicester head coach) has worked very hard with him.
"I thought he kicked very well today, I thought he controlled the game very well, and physically he put his body on the line."