Saints saw their seven-match winning streak against Harlequins shattered in a 20-9 defeat at The Stoop on Saturday afternoon.
An Alofa Alofa try, allied with three points from Nick Evans and 12 from replacement fly-half Tim Swiel saw Quins end their barren run against Jim Mallinder’s men.
Saints only had three Stephen Myler penalties to show for their efforts as they suffered their fourth defeat in six Aviva Premiership outings this season.
It was a largely disappointing display from the away side, who, a period towards the end of the first half aside, struggled to get any dominance in the game.
And Quins took advantage, pulling away during the second period to get the win they desperately wanted.
Saints had won at The Stoop in dramatic fashion back in February, with Ben Foden scoring a stunning last-gasp try.
But there was to be no stirring fightback on this occasion as uninspiring Saints finished the day without a try to their name.
Quins set the tone from the off, winning a string of early penalties, the first of which was fluffed by Kiwi kicker Evans.
But the returning No.10 soon made amends, landing a kick that came after Nic Groom had ran into danger and become isolated.
Evans was soon lining up a third shot at goal in the space of nine minutes, adding another three points to the dominant hosts’ tally.
Saints were really struggling to get out of their own half and after some poor defensive decisions saw the line broken, Alofa cruised in from the left to score.
The only saving grace for Mallinder’s men was that Evans missed yet another effort from the tee, sending the conversion wide to a backdrop of groans from the home supporters.
Myler made the Quins kicker pay at the other end with a well-struck penalty that narrowed the gap to five points.
It was soon down to just two as Quins conceded a penalty at the scrum and Myler again stuck the boot in.
Saints were really growing into the game and after some fine work by Tom Wood earned a penalty at the breakdown, they pushed on to earn another shot at goal.
Myler was to miss for the first time, rattling the post with the penalty attempt, and he failed with another effort soon after to leave his team two points down at the break.
Quins started the second half as they had the first, charging at the Saints defence and trying to force an opening.
When they did get through, Ahsee Tuala did well to stop Tim Visser and win a penalty, but Quins soon had one of their own, with Swiel, on for Evans at half-time, landing it.
Saints were finding it difficult to respond and Quins thought they had scored when Luke Wallace dotted down, but the effort was disallowed for a clear block from Visser on Ken Pisi in the build-up.
The home fans were furious with referee Ian Tempest, but the decision only served to add more fuel to their players’ fire, with Quins turning up the heat.
Swiel landed his second penalty of the half and Saints were eight points down, needing a big response in the final 20 minutes of the match.
The men in white did finally put some pressure on, with Myler landing a penalty with 15 minutes to go.
Saints needed to make that the start of a resurgence, as they had in the first period, but Quins came straight back at them, winning yet another penalty that Swiel kicked to restore their eight-point lead.
There was to be no response from Saints and Quins continued to push until the end, finishing the game with yet another effort from the tee as Swiel twisted the knife.
Harlequins: Brown; Yarde, Alofa, Roberts, Visser; Evans (Swiel 40), Dickson; Lambert (Jones 18), Buchanan (Gray 77), Sinckler (Collier 70); Merrick (Twomey 73), Horwill (c); Robshaw, Wallace, Chisholm (Luamanu 73).
Saints: Tuala (Foden 60); K Pisi, G Pisi, Burrell, North; Myler (Olver 76), Groom (Dickson 50); A Waller (E Waller 68), Haywood (Clare 76), Brookes (Hill 56); Lawes, Paterson (Dickinson 73); Wood (c), Clark (Picamoles 53), Harrison.
Referee: Ian Tempest