Tagicakibau closes in on the tryline in the dying seconds
London Irish: (14) 29
Tries: Leguizamon, Catt, Geraghty,Tagicakibau
Cons: Geraghty 3
Ulster: (13) 13
Pens: Humphreys 2
Mike Catt inspired London Irish to their first win of this year's Heineken Cup as his side battled to an entertaining home victory over Ulster.
Ulster paid the price for their failure to score when the Exiles were down to 13 men for 10 minutes after the break.
Juan Leguizamon and Catt put Irish 14-6 up but two yellow cards at the end of the first half let Ulster's Paul Steinmetz close the gap to one point.
But Irish prospered after the break and ended up with a vital bonus point.
Ulster opened the scoring through David Humphreys' 12th-minute penalty, but some sparkling back play from Catt and Mapusua allowed Exiles number eight Leguizamon to burst through under the posts.
Soon after, Irish went further ahead as Catt used all his experience to latch onto a sublime chip from Shane Geraghty, hacking on and then collecting the bouncing ball to score his side's second try.
Starved of possession, Ulster were grateful for Humphreys' long-range penalty on 34 minutes after London Irish handled in the ruck.
Several flash-points began to find their way into the match, with Ulster duo Justin Harrison and Neil Best frequently at the centre of things.
Steinmetz crosses for Ulster's only try of the match
Delon Armitage became the first London Irish player to earn a spell in the bin, his high tackle on opposite number Bryn Cunningham gave referee Joel Jutge no choice.
And the home side were reduced to 13 men moments later though, when Justin Bishop, trapped at the bottom of a ruck, cynically tripped Ulster's Issac Boss as he went to break round the fringes.
With seconds left on the clock, Ulster decided to go for touch and their adventure was rewarded when a textbook backs move gave Steinmetz the space to glide over and close the gap to one point at the break.
The stage seemed set for Ulster to forge a lead in the opening minutes of the second half, but basic errors - and canny Exiles defence - ensured the score was still 14-13 by the time Bishop returned.
A missed penalty from Humphreys on 50 minutes was the closest his side came to taking the lead, and his shout of frustration was indicative of the Exiles' growing assurance.
Catt's brilliant break from deep sparked a thrilling London Irish attack, and it took a magnificent tackle on Leguizamon to halt what would have been one of the tries of the season.
But from the resulting position deep in Ulster's 22, Geraghty dummied his way through two tackles to score under the posts.
Ulster began to force the issue, but the important passes would not stick and a long-range penalty from replacement Barry Everitt effectively sealed the vital win for the home side.
And a last-minute burst down the left touchline from Delon Armitage resulted in a superb score for winger Saliosi Tagicakibau and a priceless bonus point for his side.
London Irish boss Brian Smith on 35-year-old centre Mike Catt:
"Catt can still do a job for England - the reason he's still one of the best centres in the game is his unbelievable enthusiasm.
"At times today he was charging like the cavalry through ugly players like Neil Best who wanted to knock his block off.
"He comes to training and expects the best of himself and everyone else and doesn't take any short cuts.
"His nostrils flare when he walks onto the pitch - he's an inspiration."
Ulster assistant coach Allen Clarke:
"We got ourselves back into the game and started believing in ourselves.
"We worked through the phases and caused problems but the second half was a huge disappointment.
"We were disappointed to concede so easily in the second half. We needed to
be more precise."
London Irish: D Armitage; Bishop, Mapusua, Catt (c), Tagicakibau; Geraghty, Hodgson; Hatley, Russell, Lea'aetoa, Kennedy, Casey, Roche, S Armitage, Leguizamon.
Replacements: Collins, Coetzee, Rautenbach, Hudson, Murphy, Tiesi, Everitt.
Ulster: Cunningham; T Bowe, Steinmetz, P Wallace, Trimble; D Humphreys, Boss; Young, R Best, S Best (c), Harrison, McCullough, N Best, Dawson, Wilson.
Replacements: Shields, Fitzpatrick, Barker, McMillan, Campbell, Maggs, Bartholomeusz.
Referee: Joel Jutge (France).