A Sam Warburton try and 17 points from the boot of Leigh Halfpenny saw the Blues run out 22-15 winners at the Madejski Stadium in a nail-biting counter.
With so much at stake for both sides – Irish knew a win would keep their own European hopes alive – this was always going to be a tight affair and it proved that way with defences dominating in Reading.
Irish led 9-6 at the break as Adrian Jarvis outscored Halfpenny by three kicks to two but Warburton’s try following Casey Laulala’s fine break just a minute after the interval swung things in the visitor’s favour.
Halfpenny converted and, although, the Exiles never let go of their coat tails, the Blues were always a score ahead from there on in.
The match remained in the balance until the very last but a 75th-minute strike from the Blues full back left Irish chasing a converted score to tie things up late on.
They came close as they pressed repeatedly in a final flurry but the Blues defence followed Wales’ World Cup example and held firm under serious pressure.
Victory sets up a truly mouth-watering weekend of rugby next time out, with the Blues hosting Racing Metro 92 and Irish travelling to Edinburgh.
Justin Burnell and Gareth Baber’s troops know that if they match Edinburgh’s efforts at Murrayfield it is they who will top the pool, while achieving that target with a win would likely mean a home tie in the last eight.
