London Irish fly-half Shane Geraghty shone as the Exiles kept alive their feint hopes of qualifying for the Heineken Cup quarter-finals with victory over Ulster.

Geraghty, preferred ahead of Barry Everitt for the number 10 jersey, was in sparkling form as Ulster's own European ambitions were dealt a significant blow at the Madejski Stadium.

The 20-year-old - who has yet to opt for English or Irish Test allegiance - kicked three conversions and crowned a mature display with a well-taken try that killed off Ulster with 20 minutes to go.

Juan Leguizamon, Mike Catt and Sailosi Tagicakibau also crossed for the Exiles in a gripping and feisty Pool Five encounter - the first competitive meeting between the Guinness Premiership club and Irish opposition.

Paul Steinmetz ran in Ulster's solitary try and the visitors will be disappointed not to have been more clinical in their finishing with the boot of David Humphreys doing the rest.

The Celtic League champions have not reached the Heineken Cup knockout stages since winning the competition in 1999 and now face an uphill battle to progress further this season.

Llanelli's triumph over Toulouse earlier this afternoon has given the Welsh side a seven-point lead at the top of the pool with Toulouse, Ulster and Irish having considerable ground to make up.

An early blunder from referee Joel Jutge cost Ulster with Steinmetz slipping through the home midfield only for the official to have decided enough advantage had been played.

Winger Justin Bishop scythed through Ulster's ranks in the fifth minute and Tagicakibau carried the move on before being bundled into touch close to the left corner.

Humphreys nudged Ulster ahead with a long-range penalty but Irish took full control with two tries in three minutes.

Catt sent a miss-pass to Seilala Mapusua who drew Paddy Wallace before feeding Leguizamon with the Argentina back row breaking tackles from Bryn Cunningham and Isaac Boss and crashing over.

There was a hint of luck in Irish's second try with Geraghty chipping ahead and Catt hacking on until a kind bounce allowed him to gather up and fall over the line. Geraghty landed both conversions.

Holes continued to appear in Ulster's defence with giant Samoan centre Mapusua doing most of the damage.

Leguizamon picked up and drove over from the back of a scrum only to discover he had crossed the markings for Reading Football Club's six-yard box - three yards short of the Ulster tryline.

A Humphreys penalty reduced the deficit and Ulster were lifted by the 39th minute sin-binning of Delon Armitage for a high tackle on Cunningham after quick hands had released the visitors' backline.

Justin Bishop joined Armitage in the sin-bin for tripping Boss as the overstretched Irish defence scrambled desperately to halt waves of Ulster attacks.

Their efforts were in vain, however, as Ulster spun the ball left where they had numbers and Steinmetz skipped over with Humphreys adding the extras.

The Celtic League champions could not add to the score before Armitage and Bishop completed their 10-minute stint in the bin with the duo's return inspiring Irish.

In the 62nd minute they crossed for their third try with Geraghty dashing between Humphreys and Paddy Wallace to touch down under the posts, and the Exiles fly-half made no mistake with the extras.

Geraghty went off and Barry Everitt came on, kicking an injury-time penalty before Tagicakibau crossed moments before the final whistle to leave Ulster dead and buried.