A late drop-goal from Nick Evans proved to be the difference as Harlequins secured a narrow 22-19 victory over Worcester.
Harlequins were looking to bounce back from a narrow defeat to Bath a week earlier, while Worcester were out to secure consecutive wins following victory over Saracens.
And it was the visitors who made the stronger start to the game, setting up an eight-point lead courtesy of an early unconverted try from David Lemi, created by Chris Pennell's superb offload, and a penalty goal from Alex Goode, whose earlier conversion attempt had hit the post.
Nick Evans' penalty on 19 minutes got Quins off the mark but Goode's instant booted response restored the eight-point barrier.
Then, after Lemi was dispatched to the sin-bin for a breach at the breakdown, the two teams traded further penalties, before the hosts turned the contest on its head.
Matt Hopper steamed over four minutes before the break for Quins' first try, which Evans converted, before he knocked over a third penalty on the stroke of half-time to make it 16-14.
Meanwhile, Worcester's Semisi Taulava became the second player to be sent to the sin-bin after being pinged for collapsing the maul.
Opportunities were few and far between during the opening stages of the second half and it wasn't until the 58th minute that the deadlock was broken by an Evans penalty.
Errie Claassens' try less than ten minutes later brought Worcester level, although crucially the conversion was missed.
The scores remained deadlocked until the 74th minute, when Evans stepped up to hit over a handsome drop goal, and this time there was no way back for Worcester.
Pens: Evans 4
Tries: Lemi, Claassens
Pens: Goode 3
Harlequins: 15 Tom Williams, 14 Seb Stegmann, 13 Matt Hopper, 12 Jordan Turner-Hall, 11 Sam Smith, 10 Nick Evans, 9 Karl Dickson, 8 Nick Easter (c), 7 Luke Wallace, 6 Maurie Fa'asavalu, 5 George Robson, 4 Olly Kohn, 3 James Johnston, 2 Joe Gray, 1 Mark Lambert.
Replacements: 16 Rob Buchanan, 17 Darryl Marfo, 18 Will Collier, 19 Charlie Matthews, 20 Tom Guest, 21 Jordan Burns, 22 Rory Clegg, 23 Tom Casson.
Worcester Warriors: 15 Chris Pennell, 14 Nikki Walker, 13 Alex Grove, 12 Josh Matavesi, 11 David Lemi, 10 Andy Goode, 9 Paul Hodgson, 8 Semisi Taulava, 7 Matt Kvesic, 6 Neil Best, 5 Chris Jones, 4 James Percival (c), 3 John Andress, 2 Ed Shervington, 1 Ceri Jones.
Replacements: 16 Aleki Lutui, 17 Rob O'Donnell, 18 Euan Murray, 19 Dean Schofield, 20 Sam Betty, 21 Jonny Arr, 22 Andy Short, 23 Errie Claassens.
Referee: Luke Pearce