Harlequins' old-guard looked forever young as they schooled the Northampton nippers to kill off Saints' title hopes.
With Quins picking their first team and Northampton largely trusting their exciting kids this pitched English old versus new in front of Eddie Jones.
And his long-discarded 30-somethings Mike Brown and Danny Care dominated the early-20s up-and-comers George Furbank and Alex Mitchell.
Harlequins' old-guard looked forever young as they schooled Northampton in 30-17 victory
England boss Eddie Jones was in attendance at the Stoop as Quins crushed Saints' title hopes
By the time Quins had their bonus-point - after tries from Nathan Earle, Scott Baldwin, Chris Robshaw and Chris Ashton - Saints' youngsters looked like rabbits in headlights as the Londoners shone.
'The spine of the team played very well,' said Harlequins' Paul Gustard.
'When they play well it gives us direction in attack. Things change fast. Against Worcester we embarrassed ourselves, let the club down so today was the response we wanted.
'This next block of three games are critical if we want to make the top four.' Northampton were fourth when the league resumed but look out of the playoff race now with two wins in their last nine. They look a team for the future, but not now.
'There's not a lot of experience in that side,' said Saints boss Chris Boyd.
'It's a painful road and a painful lesson, but hopefully they'll grow.
Chris Ashton was among the four Harlequins try scorers as they secured a bonus point win
Harlequins have moved just three points behind Saints in the Gallagher Premiership table
'Top four is still alive but it's a hell of a big mountain now. The flame hasn't gone out but one more loss will be terminal I think.' Saints' youthful exuberance, and a record-breakingly porous Quins defence, contributed to the first try.
From a lineout five minutes in Mitchell fizzed a pass to New Zealander Matt Proctor who walked through Paul Lasike and Joe Marchant in the home defence - he fed Rory Hutchinson to beat Brown and the centre ran it in.
This was now the 77th Premiership match in a row that Quins had conceded a try - a league record.
After Marcus Smith knocked over a penalty Harlequins replied properly. Ryan Olowofela was a victim of his own fast feet as he broke away from his Saints support just outside his 22, became isolated and gave away a penalty.
Brown looked up and took it quickly, performed a sublime one-two with Alex Dombrandt then floated a fine pass out left to Earle for the score.
The dominant victory for Harlequins was just their third victory in the league since February
Up the other end James Grayson flicked an equally excellent ball to Olowofela on the blind-side for Saints' next try, which he converted like the first, but Quins came straight back.
From a rolling maul Scott Baldwin bashed over and although Smith missed the kick he took a penalty on half-time to give Quins a four-point lead.
After the break Smith helped extend that. The 21-year-old jinked through and suddenly Quins were in. A couple of phases later and Ashton zipped a pass to Chris Robshaw to score on the left wing.
Then the clincher. Brown was rolling back the years at this point. He dummied a clearance kick in his 22, raced through then offloaded without looking to Dombrandt who saw Ashton racing up on the right.
The winger finished his 88th league score with the signature 'Ash Splash' and Smith converted. In the blink of an eye Quins led by 16 and had a bonus point.
Grayson hit a penalty on the hour but in a din of whoops and hollers Quins shut Saints out for just a third league win since February.
