Stand-in captain Chris Malone kicked Harlequins to a 26-25 Guinness Premiership victory over Wasps in their London derby on Saturday at the Stoop.
Fly-Half Malone contributed 16 points in an exiting clash which saw the lead change hands five times.
Malone landed three penalties, two conversions and a drop goal after creating his side's opening try for centre Tosh Masson.
Malone's 66th-minute conversion finally secured victory, after a sustained spell of forward pressure produced a try for replacement back-row forward Tom Guest.
Spurning the chance of a penalty goal, Quins cracked the Wasps defence after winning the resulting line-out.
The visitors repelled four drives by the Harlequins pack, but a massive surge forced the resulting scrum over the try-line for Guest to touch down.
Malone was fortunate not to be punished for missing two simple late penalty chances when Wasps replacement Dave Walder saw his long-range drop goal attempt drift narrowly wide deep into injury time.
Wasps had earlier scored two tries via centre Fraser Waters and one from Ireland's World Cup scrum half Eoin Reddan.
But Danny Cipriani miscued a 74th-minute penalty which would have given them victory, having already landed two conversions and a penalty.
The other Wasps point came from a superb first-half drop goal from centre Riki Flutey.
Masson, making his first start of the season, got Quins off to a flying start with his fourth-minute try.
He reacted quickly to score between the posts following a short probing kick through the middle by Malone.
Another kick from Malone, in the 10th minute, just failed to find Ugo Monye on the left wing.
Wasps hit back a minute later through Reddan, who reacted quickly when the home side spilled the ball just inside their own half and ran 50 metres for his try.
Harlequins were reduced to 14 men when scrum-half Danny care was dispatched to the sin-bin for 10 minutes for illegally preventing opposite number Reddan from taking a quick tap penalty.
Capitalising on the extra man advantage, Wasps moved the ball wide to the right for Waters to outstrip the Quins' defence on a 40 metre run to the line for his first try.
But when Reddan was shown a yellow card in the second half, after taking an opponent off the ball, Wasps found themselves up against it - and Harlequins utilised the temporary numerical advantage to produce Guest's crucial try.
Tries: Masson, penalty try
Cons: Malone 2
Drop goal: Malone
Tries: Reddan, Waters 2
Cons: Cipriani 2
Drop goal: Flutey
Yellow cards: Care (Harlequins, 23), Reddan (Wasps, 55)
Harlequins: 15 Mike Brown, 14 David Strettle, 13 Hal Luscombe, 12 Tosh Masson, 11 Ugo Monye, 10 Chris Malone (c), 9 Danny Care, 8 Chris Hala'Ufia, 7 Will Skinner, 6 Chris Robshaw, 5 Jim Evans, 4 Nicolas Spanghero, 3 John Brooks, 2 Tani Fuga, 1 Ceri Jones
Replacements: 16 Chris Brooker, 17 Mike Ross, 18 James Percival, 19 Tom Guest, 20 Simon Keogh, 21 Adrian Jarvis, 22 Jordan Turner-Hall
London Wasps: 15 Mark Van Gisbergen, 14 David Doherty, 13 Fraser Waters, 12 Danny Cipriani, 11 Tom Voyce, 10 Riki Flutey, 9 Eoin Reddan, 8 James Haskell, 7 Rob Webber, 6 John Hart, 5 George Skivington, 4 Richard Birkett, 3 Nick Adams, 2 Joe Ward, 1 Tim Payne
Replacements: 16 Michael Holford, 17 Charlie Beech, 18 Dan Leo, 19 Hugo Ellis, 20 Simon Amor, 21 Dave Walder, 22 Rob Hoadley
Referee: Dean Richards
Touch judges: Ken Stewart, David Kurk
Assessor: Ed Morrison