Conor O'Shea converted a dramatic injury-time drop goal to ruin Leicester's dreams of reaching the Premiership summit and seal an historic win at Sunbury last night.
The Exiles faithful have waited six months for a prize home victory and despite a bitterly cold capital night nothing was going to stop them enjoying the party.
The Tigers enjoyed all the early domination but paid for their failure to convert pressure into points. However, Dick Best's side soon settled to prove that despite their contrasting league fortunes there was little to separate the two sides.
In fact it was London Irish who showed the more imagination, capitalising on a mistake by former England full-back Tim Stimpson to drive down-field and lay siege to the Leicester line.
The visitors bravely battled to repel their advances but when the ball was spread wide to O'Shea, the Exile captain's electric pace left Leicester flat footed.
However, it wasn't long before Best's men were also feeling redfaced with the Tigers launching an immediate revenge attack - winger Leon Lloyd touching down just seconds after the restart.
A flurry of penalties from Joel Stransky's unerring boot followed, giving the visitors a slender three-point advantage at the break.
But after so long patiently waiting for an elusive home win it was always going to be a night for London Irish. The second half was just two minutes old when Nick Burrows's break set up lock Malcolm O'Kelly for a rare break over the try-line.
Niall Woods increased the advantage with a couple of precision penalties but Best's men knew the Tigers were far from tamed.
Ever-reliable Stransky calmly buried his third penalty while scrum-half Austin Healey raced home from a ruck 20-yards out to recapture the lead for Dean Richards's troops.
London Irish mounted a strong late challenge but Leicester held firm until O'Shea delivered the killer blow in the most thrilling way.
London Irish: O'Shea; Bishop, Burrows, Vanter, Woods; Jones, Campbell; Worsley, Kirke, Fullman, Harvey, O'Kelly, Boer, Gallacher, Dawson. Replacements: Brown for Jones 65 mins, Richards for Campbell 65 mins, Todd, for Bishop 61 mins, Spicer for Boer 65 mins. Not used: Howe, Hardwick, Bird.
Leicester: Stimpson; Lloyd, Greenwood, Howard, Ezulike; Stransky, Healey; Jelley, West, Garforth, M Johnson, Van Heerden, Gustard, Back, Corry. Replacements: Horak for Stimpson 21 mins, Freshwater for Jelley 63 mins, Fletcher for Van Heerden 11 mins. Not used: Cockerill, Stuart, Hamilton, Moody.
Referee: S Lander.
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