James Wilson scored the only try of the match as Northampton Saints beat Harlequins 16-6 in the Aviva Premiership.
Wet conditions made handling the ball difficult at the Stoop, while Nick Evans missed two penalty attempts for the home side in the opening half.
Evans's issues with his kicking continued as he missed a chance to add three more points at the start of the second half, before another effort hit the post later in the game.
Harlequins won a scrum with just over 15 minutes left to play, but Danny Care's attempted kick forward was blocked by Northampton, setting up Wilson for the only try of the game.
Both sides ended the game with 14 players on the pitch, as Evans and Stephen Myler were both sent to the sin bin for deliberate knock-ons.