A 76th-minute penalty from fly-half Adrian Jarvis saw London Irish edge past Sale 21-19 at Madejski Stadium on Sunday.
Sale opened up a 10-0 lead through a converted try from Rob Miller and a Nick Macleod penalty, but Irish dominated the rest of the first half.
Bryn Evans barged over and then Topsy Ojo touched down as the hosts led 12-10 at the break.
Three penalties by Macleod put Sale 19-18 up, after Irish had responded with two of their own from Tom Homer and Adrian Jarvis. But Jarvis was the hero with a late three-pointer.
It was the visitors who started the brighter, pressurising the Irish 22. And they were rewarded after just five minutes when Miller darted over after good work from Richie Vernon and Johnny Leota.
The Sharks have impressed in recent weeks, emphasised by their narrow 28-23 defeat to Leicester Tigers last week, and they continued that form early on in this encounter. And Macleod converted a penalty opportunity to establish a 10-point advantage for the away side.
However, Sale's tendency to overplay was exploited to the full by the hosts when they turned over opposition ball. After numerous phases, Evans drove across the whitewash and it was Irish who began to control proceedings as they took the lead for the first time when Ojo touched down.
Just like the opening period, the Sharks dominated initial stages of the second half and took the lead through the boot of Macleod after David Paice was sin-binned.
But Homer restored Irish's advantage before the visitors' fly-half edged them ahead. Jarvis and Macleod traded three-pointers before the hosts' number ten kicked a late penalty to snatch the win.
For London Irish:
Tries: Evans, Ojo
Pens: Homer, Jarvis 2
For Sale Sharks:
Pens: Macleod 4
Yellow card: Paice (London Irish -48th min)
London Irish: 15 Delon Armitage, 14 Topsy Ojo, 13 Jonathan Spratt, 12 Shontayne Hape, 11 Tom Homer, 10 Adrian Jarvis, 9 Darren Allinson, 8 Alex Gray 7 Jamie Gibson, 6 Bryn Evans, 5 Matt Garvey, 4 Nick Kennedy, 3 Paulica Ion, 2 David Paice, 1 Clarke Dermody (c).
Replacements: 16 James Buckland, 17 Alex Corbisiero, 18 Faan Rautenbach, 19 Bob Casey, 20 David Sisi, 21 Adam Thompstone, 22 Steven Shingler, 23 Paul Hodgson
Sale Sharks: 15 Rob Miller, 14 Tom Brady, 13 Johnny Leota, 12 Sam Tuitupou (c), 11 Joaquin Tuculet, 10 Nick Macleod, 9 Dwayne Peel, 8 Andy Powell, 7 Onosa'i Auva'a, 6 Richie Vernon, 5 James Gaskell, 4 Fraser McKenzie, 3 Tony Buckley, 2 Marc Jones, 1 Alasdair Dickinson.
Replacements: 16 Andy Titterrell, 17 Lee Imiolek, 18 Vadim Cobilas, 19 Kearnan Myall, 20 Mark Easter, 21 Cillian Willis, 22 Luther Burrell, 23 Will Addison.
Venue: Madejski Stadium
Referee: Wayne Barnes