Wasps clinched a thrilling 21-20 win over London rivals Harlequins in front of 80,000 at Twickenham in the Guinness Premiership on Sunday.
Danny Cipriani endured a frustrating return to action as Wasps made heavy weather of dispatching their capital rivals.
The chief culprit was Cipriani, who was starting for the first time since recovering from a hairline leg fracture in early October.
Cipriani missed five of his seven shots at goal and although all the kicks were from a challenging position, England's sixth choice fly-half will have been disappointed with the return.
Never more than competent in open play, the 22-year-old was eclipsed by Dave Walder - his 57th minute replacement.
Walder has been in commanding form in the Wasps' number 10 jersey but lost his place in the starting line-up to Cipriani, who is reported to have held talks with Stade Francais over a move to Paris next season.
Out to show Wasps management they had made an error in selection, Walder kicked five points and expertly steered his side to victory in the final quarter.
Scrum-half Joe Simpson and back row John Hart crossed for the winners while Danny Care and David Strettle scored Quins' tries in a lively encounter.
Simpson saw Wasps surge ahead with just two minutes on the clock, the move started when lock George Skivington escaped from a breakdown five yards inside his own half.
After galloping 25 metres he chipped ahead but Strettle made a mess of the kick, allowing the ball to squirt free and Simpson was on hand to gather and touch down.
Quins' error-strewn display continued but two penalties from Nick Evans settled the nerves and they began to stamp their authority on the match.
Cipriani landed a difficult penalty but missed a 60-yard attempt.
Showing patience, Wasps strung together several phases with England lock Simon Shaw carrying with intent and the pressure was getting to Quins who began to come off worse on the penalty count.
Cipriani booted another three points after Monye had flopped onto Shaw to nudge Wasps 11-6 into the lead.
Evans missed two penalties in succession and although kicks were dominating the scoreboard, the match was being played at an entertaining pace.
Quins tighthead Mark Ross was being given a torrid time at the scrum by Tim Payne, who was proving an integral part of a dominant Wasps pack.
But their superiority on the scoreboard continued to be hampered by Cipriani's kicking with the England fly-half missing a further two penalties, though they were tricky attempts.
Simpson was given oxygen as was led from the pitch clutching his left wrist and moments later his half-back partner Cipriani squandered a fifth shot at goal.
He was replaced by Walder with just over a quarter remaining but the newcomer's first involvement was to see his clearance charged down by Evans.
Where Cipriani had failed repeatedly, however, Walder succeeded by landing a tricky penalty only for Quins to peg back the deficit to one point when Care dived over from a close-range breakdown with Evans converting.
Wasps' response was magnificent, the impressive Walder and man of the match Shaw involved before Dan Ward-Smith sent blindside Hart over.
In another nudge to the Wasps management that he should have been on from the start, Walder slotted the conversion to put the match beyond Quins.
Strettle raced over as Quins finished with a flourish but there was no time to complete the comeback.
Tries: Care, Strettle
Cons: Evans 2
Pens: Evans 2
Tries: Simpson, Hart
Pens: Cipriani 2, Walder
Harlequins: 15 Mike Brown, 14 David Strettle, 13 Gonzalo Tiesi, 12 Nils Mordt, 11 Ugo Monye, 10 Nick Evans, 9 Danny Care, 8 Nick Easter, 7 Will Skinner (c), 6 Chris Robshaw, 5 George Robson, 4 Lewis Stevenson, 3 Mark Lambert, 2 Tani Fuga, 1 Ceri Jones.
Replacements: 16 Chris Brooker, 17 Aston Croall, 18 John Andress, 19 James Percival, 20 Tom Guest, 21 Karl Dickson, 22 Rory Clegg, 23 George Lowe.
London Wasps: 15 Mark Van Gisbergen, 14 Paul Sackey, 13 Dominic Waldouck, 12 Steve Kefu, 11 David Lemi, 10 Danny Cipriani, 9 Joe Simpson, 8 Dan Ward-Smith, 7 Serge Betsen (C), 6 John Hart, 5 George Skivington, 4 Simon Shaw, 3 Ben Broster, 2 Rob Webber, 1 Tim Payne.
Replacements: 16 Joe Ward, 17 Martin Rice, 18 Bob Baker, 19 Dan Leo, 20 Will Matthews, 21 Mark Robinson, 22 Dave Walder, 23 Ben Jacobs.