Defeat at the Madejski Stadium ends the Ospreys hopes of a fourth consecutive place in the knockout stages.
There was disappointment for the Ospreys as they fell to their third defeat of the Heineken Cup campaign to at the Madejski Stadium on Sunday afternoon.
Irish went into the game on the back of a 10 game losing streak, but led from the early stages as the Ospreys failed to secure the win that would have set-up a winner takes all clash against Toulon at the Liberty Stadium next Saturday, with Sailosi Tagicakibau and Topsy Ojo scoring the only tries of the game.
The Ospreys came racing out of the blocks at the first whistle, putting the Irish line under pressure straight away. Mike Phillips collected the ball straight from the restart, and his side went through the phases looking for an opening, Dan Biggar and Richard Hibbard both carrying well, but they were unable to find their way through as the Irish defence held firm on their line, both Phillips and Marty Holah being held up short .
After weathering the early storm Irish came into it and Nikki Walker had to be alert to ground a bouncing ball behind his line following a speculative Dan Bowden box kick that allowed his team-mates to chase.
It was Irish who opened the scoring 15 minutes in, Bowden slotting over a straightforward three points after Marty Holah was guilty of coming in from the side.
The Ospreys responded positively, Hibbard, Alun Wyn Jones and Jerry Collins all carrying well, before referee George Clancy penalised Irish for a similar offence, Biggar levelling.
It was level for just a minute though, Irish hitting back with the first try of the afternoon. Delon Armitage broke through ineffective tackling on halfway, the ball was moved through the hands, before Armitage was able to throw a long miss pass to wing Tagicakibau who powered over the line to make it 8-3, Bowden missing with a difficult conversion attempt from the touchline.
The fly-half had more success with his next attempt, a penalty to extend the Irish lead in the 29th minute after Adam Jones was penalised for not binding in the scrum.
Biggar then put over his 2nd penalty of the afternoon from the 10m line after Irish were pinged at the ruck once again.
A series of pick and drives then took Irish back into the Ospreys 22, but fierce defence frustrated the hosts, forcing Bowden to kick loosely straight into touch when more patience could have reaped better dividends for his team.
With half time approaching and the rain starting to fall Bowden was able to extend his team’s lead with a long range effort.
HALF TIME: LONDON IRISH 14 OSPREYS 6
The Ospreys needed a positive start to the second half but it was the hosts who scored almost immediately, Ojo racing through to score under the posts after a strong run by former Osprey Elvis Seveali'i to allow Bowden a simple conversion.
Biggar responded with his third successful penalty, from inside the Ospreys half, but in the 48th minute he was off target with an effort closer to goal, his attempt just drifting to the right. With 55 on the clock he had another opportunity but again failed to hit the target.
With the clock ticking away the Ospreys were becoming increasingly desperate as they looked for a way back, and despite going through numerous attacking phases they were unable to find a way through. With Biggar off, James Hook moved to fly half for the final quarter, taking over kicking duties, and his first attempt in the 65th minute reduced the deficit to nine points.
Poor discipline handed Irish an opportunity to hit straight back but for Bowden was unable to take advantage, missing the penalty.
Irish were reduced to 14 for the final ten minutes when James Buckland was sinbinned for tackling a player without the ball as the Ospreys edged ominously close to the opposition line.
Instead of taking the three points the Ospreys opted for a scrum, from which they looked to power their way over from close range. The fantastic travelling support were roaring the team on and the players tried to respond, going left and right, but there was no way through and when Collins was pinged for not releasing, Irish were able to clear their lines.
It was becoming increasingly desperate and frantic as the Ospreys involvement in the Heineken Cup this season was ebbing away, and Ryan Lamb put the final nail in the coffin with two minutes to go, with a penalty after Jamie Nutbrown tackled the man without the ball.