A strong second half saw London Irish hold on for an 18-13 Premiership win over Harlequins and Madejski Stadium on Saturday.
Two quickfire tries in the second half proved crucial as Irish edged to a hard-fought victory over the 2012 champions.
Neither team headed into the game in good form. Irish had been beaten by Bath a week earlier, while Harlequins suffered a home reverse against Saracens.
Try-scoring opportunities were few and far between in the first half, with the two goal-kickers exchanging penalties in a tight opening period.
Shane Geraghty put Irish 3-0 up on eight minutes and it remained that way until Nick Evans levelled the scores ten minutes later following home indiscipline.
Geraghty restored the narrow advantage in the final ten minutes of the first half, but it was level at the interval thanks to Evans' sweetly struck second penalty.
The tight, defence-dominated nature of the game was again apparent after the interval, and neither team appeared capable of taking the contest by the scruff of the neck.
But the pace of the game changed on the hour, when debutant Blair Cowan's converted try for the Exiles gave the hosts a seven-point lead.
Irish added a second a few short minutes later when Alex Lewington latched onto Topsy Ojo's clever chip to score, though the conversion was wide.
The visitors were left shell-shocked by the quickfire double concession, but Quins burst into life ten minutes from the end to ensure a grandstand finish.
Danny Care snuck over down the blind side for Evans to convert, and the comeback was on. But the home defence stood firm and, with time against on their side, Irish held out for an important win.
For London Irish:
Tries: Cowan, Lewington
Pens: Evans 2
London Irish: 15 Topsy Ojo, 14 Marland Yarde, 13 Fergus Mulchrone, 12 Eamonn Sheridan, 11 Alex Lewington, 10 Shane Geraghty, 9 Tomás O'Leary (c), 8 Ofisa Treviranus, 7 Blair Cowan, 6 Kieran Low, 5 Ian Gough, 4 George Skivington, 3 Leo Halavatau, 2 David Paice, 1 John Yapp.
Replacements: 16 Jimmy Stevens, 17 Matt Parr, 18 Jamie Hagan, 19 Ian Gough, 20 Jebb Sinclair, 21 Sailosi Tagicakibau, 22 Myles Dorrian, 23 Darren Allinson.
Harlequins: 15 Mike Brown, 14 Sam Smith, 13 Matt Hopper, 12 Tom Casson, 11 Ugo Monye, 10 Nick Evans, 9 Karl Dickson, 8 Tom Guest, 7 Chris Robshaw (c), 6 Maurie Fa'asavalu, 5 George Robson, 4 Nick Easter, 3 Will Collier, 2 Rob Buchanan, 1 Joe Marler
Replacements: 16 Dave Ward, 17 Mark Lambert, 18 Kyle Sinckler, 19 George Merrick, 20 Luke Wallace, 21 Danny Care, 22 Ben Botica, 23 Charlie Walker.
Venue: Madejski Stadium
Referee: David Rose
Assistant referees : Kevin Stuart and Roger Baileff
TMO: David Sainsbury