Six penalties from Nick Evans handed Harlequins a gritty 18-9 victory over Northampton Saints at Franklin's Gardens.
The Quins pack stamped their authority on the match very early on, winning a penalty in the opening few minutes for the ever-reliable Evans to slot over and give them the lead.
Stephen Myler levelled the scores before long though as the home side worked their way back into the match and Ben Foden was denied the game's opening try after play was called back for a forward pass.
Both kickers were also guilty of missing relatively easy chances from the tee in rather damp and soggy conditions underfoot but Evans did manage to give the visitors a slender 6-3 lead at the break with his second penalty of the afternoon.
James Johnston, who was a driving force for his team in the scrum and the loose throughout, blotted his copybook with a yellow card for not rolling away early in the second half and Myler punished the ill-discipline with another three points to level the scores.
They were the only points they could muster during their ten-minute spell with an extra man though and Harlequins gradually began to show their champion calibre by dominating possession and territory more and more as the game wore on.
And, while they were unable to create any real try-scoring opportunities, their Kiwi fly-half Evans found his kicking boots to take full advantage with three further penalties.
Replacement Ryan Lamb did look like he had rescued a bonus point for the Saints with five minutes remaining but, after good work from the forwards close to the line, Evans took that away from them as well with a sixth penalty right on the stroke of full-time.
Pen: Myler 3
Pens: Evans 6
Yellow Card: Johnston
Northampton Saints: 15 Ben Foden, 14 Ken Pisi, 13 George Pisi, 12 Tom May, 11 Jamie Elliott, 10 Stephen Myler, 9 Lee Dickson, 8 Gerrit-Jan van Velze, 7 Phil Dowson, 6 Tom Wood, 5 Courtney Lawes, 4 Samu Manoa, 3 Paul Doran-Jones, 2 Mikey Haywood, 1 Soane Tonga'uiha.
Replacements: 16 Ross McMillan, 17 Alex Waller, 18 Brian Mujati, 19 Mark Sorenson, 20 Calum Clark, 21 Martin Roberts, 22 Ryan Lamb, 23 Luther Burrell.
Harlequins: 15 Mike Brown, 14 Tom Williams, 13 Matt Hopper, 12 Tom Casson, 11 Ugo Monye, 10 Nick Evans, 9 Danny Care, 8 Nick Easter, 7 Chris Robshaw (c), 6 Maurie Fa'asavalu, 5 George Robson, 4 Olly Kohn, 3 James Johnston, 2 Joe Gray, 1 Joe Marler.
Replacements: 16 Dave Ward, 17 Mark Lambert, 18 Will Collier, 19 Charlie Matthews, 20 Tom Guest, 21 Karl Dickson, 22 Ben Botica, 23 Sam Smith.