The highlight of the match was an outstanding performance by Saracens Fly half Derick Hougaard, who scored all 24 of his sideÃ¢â‚¬â„¢s points. Four penalties from the boot of Shane Geraghty and a try from wing Paul Diggin were rare highs on a disappointing day for Saints.
The visitors had looked dominant in the early phases of the season but looked out of sorts on a greasy pitch in Watford.
Hougaard led from the front immediately and alleviated any pressure that was thrown at his side, despite having a lucky escape when an attempted clearance kick was charged down and almost converted.
The defeat sees Saints leapfrogged at the top of the table by London Irish, who impressed with a dominant win over Newcastle Falcons.
A hat-trick by Exiles winger Topsy Ojo, as well as 16 points from the boot of Ryan Lamb moved the Reading side top with a 46-12 victory.
Leicester Tigers were also in imperious form and bounced back from their defeat to bitter rivals Wasps last week with a 48-6 win over relegation favourites Leeds Carnegie at Welford Road.
Despite having both first and second choice fly halfs out to injury, a mature performance from youngster Billy Twelvetrees, and a host of tries from TigersÃ¢â‚¬â„¢ old heads Tom Croft and Alesana Tuilagi compounded LeedsÃ¢â‚¬â„¢ woes, rooting them to the foot of the table.
Elsewhere, Gloucester won narrowly at home 22-20 against London Wasps after a last-minute penalty miss from Dave Walder handed the West Country side the win in front of a partisan crowd at Kingsholm.
And Harlequins brought newly-promoted side Exeter back down to earth with a resounding 40-13 victory at the Stoop, while Bath completed a 31-16 victory over Sale at the Rec.
This weekend’s Aviva Premiership results in full:
Bath 31-16 Sale
Gloucester 22-20 Wasps
Harlequins 40-13 Exeter
Leicester 48-6 Leeds Carnegie
Newcastle 12-46 London Irish
Saracens 24-17 Northampton
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BIOGRAPHY: Cesc Fabregas