London Irish came out on top in game of penalties at the Madjeski Stadium.
Chris Malone kicked four and Tom Homer one for Irish while Rory Clegg landed three for Harlequins, who had won 10 of their 11 matches before this setback.
Irish made a strong start and a clever kick through from Malone resulted in a five-metre scrum. From it Will Skinner was penalised for offside and Malone kicked his first penalty. The lead was short lived as Clegg responded with a penalty and soon afterwards landed an excellent long range effort to give the visitors a 6-3 lead after 10 minutes.
When Quins prop Joe Marler was penalised for a deliberate knock down, he was fortunate not to pick up a yellow card and Irish did not take any advantage as Malone fired wide with his 40 metre kick. However Quins quickly gave away another penalty at a scrum and Malone made no mistake with this kick to level it at 6-6 at the end of the first quarter.
There was very little for the crowd to enthuse about for the first 25 minutes with neither side threatening the try line. Irish were shading the game in terms of territory and possession and Daniel Bowden did make a couple of strong runs to cause some concern to the Quins defence but they had to rely on Malone to kick another penalty to give them a deserved lead.
Quins full-back Mike Brown produced the most creative moment of a dull first half when he beat two players in his own 22 to send his side away on a flowing 40 metre movement. Irish were penalised and Clegg was again on target with his 45 metre kick. For Irish Tom Homer hit a post with a penalty attempt from halfway and with the last kick of the half Malone did likewise with his 35 metre kick to make it 9-9 at the interval.
The opening 10 minutes of the second half mirrored the first half action with neither side able to build up any sustained period of pressure. Paul Hodgson, the Irish scrum half, did gain valuable ground for his side with some clever box kicking but once again the next points on the scoreboard came form a penalty with Homer kicking Irish into the lead after 52 minutes.
Irish came nearest to scoring a try when a kick through from Seilala Mapusua narrowly escaped the clutches of Steffon Armitage as the flanker attempted to scoop up the ball to score.
Quins were then dealt a severe blow when Jordan Turner-Hall was sent to the sin bin for offside at the ruck and Malone was successful with the resulting penalty to give the hosts a 15-9 lead after 63 minutes. Following his penalty success, Malone was immediately replaced by Ryan Lamb who within seconds was required to play at scrum half as Hodgson was sent to the sin bin.
However, 14-a-side did not provide any more excitement and no further score resulted in the final 15 minutes.