Wasps 21-25 Harlequins
Monye has impressed in the England Sevens side
Wasps finished the regular season second in the Zurich Premiership despite a home defeat by Harlequins that ended their seven-match unbeaten run.
Quins defied their reputation as poor travellers to build a comeback win on the back of two tries from Ugo Monye and snatch a place in the Zurich Wildcard play-offs.
Fly-half Paul Burke opened the scoring for the visitors in the sixth minute with a curling, long-range penalty.
all guilty thinking we were going to win comfortably
However, Wasps went ahead in the 23rd minute as the pack surged forward for prop Craig Dowd to touch down.
Stand-off Alex King added the conversion and followed up with a penalty.
Quins lost centre Chris Bell to the sin-bin during the first half but went into the break trailing only 10-8 after England Sevens star Monye had beaten opposite number Kenny Logan to score his first try.
Tries: Dowd, Logan
Pens: King 3
Tries: Monye 2, Powell
Cons: Burke 2
Logan replied swiftly and in kind, however, taking a scoring pass from Fraser Waters in the 43rd minute.
King's conversion attempt fell short but when he followed up with another penalty soon after, Wasps looked to be building a winning lead.
However, a defensive lapse cost them dearly as Quins scrum-half Matthew Powell was first to the loose ball to touch down a try converted by Burke.
We were very good in the tackle area, we were better once it went to the
The visitors then moved ahead in the 65th minute when Monye scored his second try, Burke again slotting the conversion.
King reduced the deficit to just one point with a successful penalty, but Burke rifled through a drop goal in the 74th minute to seal Quins' victory and set up a Wildcard semi-final against Leicester next week.
Wasps: Van Gisbergen; Lewsey, Waters, Denney, Logan; King, Wood; Dowd, Greening, Green, Shaw, Birkett, Worsley, Volley, Dallaglio.
Replacements: Howley, Erinle, Rudd, Lock, Scrivener, Mackenzie, Leota.
Harlequins: N Williams; Monye, Bell, Deane, Luger; Burke, Powell; Jones, Hayter, Dawson, Rudzki, Miall, Winters, Vos, Diprose.
Replacements: Fuga, Gomez, Evans, Sheriff, Sanderson, Bemand, Gollings.
Referee: Steve Leyshon (RFU)