Ulster avenged their defeat by London Irish last weekend
Ulster (5) 29
Tries: Trimble, Humphreys, McMillan, Steinmetz.
Cons: Humphreys (3)
London Irish (6) 13
Pens: Geraghty (2)
Cons: Geraghty 1
Ulster kept their Heineken Cup hopes alive by claiming a bonus-point victory over London Irish at Ravenhill.
Irish led 6-5 after a poor first half with Andrew Trimble's try cancelled out by two Shane Geraghty penalties.
David Humphreys' opportunist try then turned the game in Ulster's favour after he had taken a tap penalty.
Neil McMillan's try extended the lead to 22-6 and while Gonzalo Piesi replied for Irish, Paul Steinmetz's late try ensured the home side's bonus point.
London Irish coach Brian Smith will be hugely disappointed by his team's second-half display and the Exiles' hopes of qualification now are almost certainly over.
Geraghty's 15th-minute penalty edged the visitors ahead but Ulster hit back three minutes later when Trimble fielded Humphreys' diagonal kick behind the London Irish defence and crossed for a try.
Ulster scrum-half Isaac Boss was yellow carded for a high tackle on Delon Armitage in the 26th minute but Geraghty's second penalty of the night was Irish' only score during their 10 minutes of numerical advantage.
London Irish were without injured Mike Catt after the interval and his absence clearly affected the visitors.
The visitors were caught totally napping by Humphreys' 44th-minute try with the Ulster fly-half appearing set to kick for goal, only to take a tap penalty and run in unopposed.
There will be arguments over whether Humphreys was breaching the spirit of the game but there was no doubt about London Irish' complete lack of concentration.
Another Humphreys penalty extended Ulster's lead to 15-6 and they were on the brink on the bonus point when replacement McMillan crossed for his side's third try in the 58th minute after a Justin Bishop mistake.
Replacement Gonzalo Piesi breached the Ulster defence to help cut the deficit to 22-13 after 62 minutes but it only served to increase the home side's resolve.
They put Irish under severe pressure and the visitors then lost Bob Casey to the sin bin six minutes from time.
As the pressure continued, the Irish defence finally cracked when Steinmetz weaved his way over to secure Ulster's fourth try and the bonus point four minutes from time as the home side comprehensively avenged last weekend's defeat.
Ulster fly-half David Humphreys:
"I can't take too much credit (for my try) apart from running it in. Simon Best just said: 'There's nobody there' and away we went.
"We were obviously going to kick at goal but for whatever reason, there was nobody in front as the referee blew the whistle. It was just one of those lucky moments.
"It's been a difficult week for a number of reasons but this performance shows the quality of the squad and the character that is in the squad.
London Irish coach Brian Smith:
"We came back and scored a try of our own but they were always more than two scores away from us and they thoroughly deserved their win.
"He (David Humphreys) was very clever. Our players thought he was down on one knee and starting to look like he was getting ready to prepare for a kick. He obviously hasn't indicated to the referee.
"I'm not sure about the spirit of the game and the rest of it but having been in that position myself, I appreciate it and he deserves it."
Ulster : B Cunningham, M Bartholomeusz, P Steinmetz, P Wallace, A Trimble, D Humphreys, I Boss, J Fitzpatrick, R Best, S Best (capt), J Harrison, M McCullough, N Best, K Dawson, R Wilson. Replacements: S Young for Bartholomeusz (80), Maggs for Wallace (62), Campbell for Boss (78), B Young for J. Fitzpatrick (62), Shields for R. Best (80), Barker for McCullough (67), McMillan for Dawson (55).
Sin Bin: Boss (26), Trimble (80).
London Irish: D Armitage, T Ojo, S Mapusua, M Catt (capt), J Bishop, S Geraghty, P Hodgson, N Hatley, D Coetzee, T Lea'aetoa, N Kennedy, R Casey, K Roche, S Armitage, J Leguizamon.Replacements: G Tiesi for Catt (41), Everitt for Geraghty (68), Rautembach for Hatley (45), Paice for Coetzee (55), Collins for Lea'aetoa (45), J Hudson for Kennedy (68), P. Murphy for Leguizamon (60).
Sin Bin: Casey (74), D. Armitage (80).
Referee: Christophe Berdos (France)