London Irish recorded a fifth successive Guinness Premiership away win and remained firmly on course for the title play-offs as they subdued 14-man Worcester at Sixways.

Worcester played the final 25 minutes without South African full-back Thinus Delport, who was sent off after receiving a yellow card for punching. He had earlier been sin-binned following a late tackle on opposite number Delon Armitage.

Delport also claimed a first-half try, but Irish prevailed - after Shane Drahm's late long-range penalty miss - through touchdowns from lock Kieran Roche and centre Shane Geraghty, with fly-half Riki Flutey booting one conversion.

Irish's victory lifted them into third place above Leicester, ahead of remaining league games against Leeds, Wasps and Saracens.

For their part, Worcester remain in contention for a top-six finish - and possible Heineken Cup qualification next season - but Delport's dismissal cost them any realistic chance of bursting the Irish bubble, despite Drahm's 63rd-minute penalty securing a losing bonus point.

Once again though, there was the unsatisfactory scenario of a Premiership game going to uncontested scrums after Worcester's front-row options ran out, and it dulled the final 30 minutes of an otherwise fierce encounter.

Irish, unbeaten on the road in Premiership combat since late November, were dealt a double injury blow as captain Mike Catt and wing Samoan wing Sailosi Tagicakibau missed out.

Influential centre Catt was sidelined by a back strain sustained during the European Challenge Cup quarter-final victory over Bayonne last weekend, so England Under-21 international Geraghty replaced him in midfield alongside Australian rugby league import Paul Franze.

A minor leg injury frustrated Tagicakibau, meaning a start for Justin Bishop, while Worcester skipper Pat Sanderson continued his return from back trouble which saw him miss England's entire RBS 6 Nations Championship campaign, making a first Sixways appearance for four months.

Irish underlined their status as one of the Premiership's form teams by storming into a third-minute lead.

They maintained territorial dominance after Flutey kicked off, and the fly-half tormented Worcester's defence by switching attacking direction on more than one occasion, and his adventure gained its reward when Roche powered over following a 15-metre charge.

Flutey could not land the touchline conversion, and he was left cursing himself after missing a simple penalty chance five minutes later as the Irish siege continued, with flanker Declan Danaher only being denied a try by some last-ditch tackling.

Worcester appeared in all kinds of strife, but Sanderson sparked a stirring response, breaking out from inside his own half and prompting some slick passing that ended with Delport smashing through the Irish defence for an equalising try.

It was a perfect way for Delport to celebrate signing a new contract with the Warriors, and Drahm's conversion gave Worcester an unlikely 7-5 advantage.

Delport was then rightly sin-binned him for a late challenge on Armitage, temporarily reducing Worcester to 14 men as the game continued at a frantic pace.

Irish though, failed to score before Delport returned, with Worcester aggressively battling for control up-front, and it took a lengthy Flutey touchfinder to relieve escalating Warriors pressure.

The home side suffered an injury setback midway through the second quarter when their South African hooker Andre Van Niekerk was carried off following a three-minute stoppage.

Van Niekerk's injury appeared serious, yet Worcester displayed admirable character and should have extended their lead when Drahm lined up an easy 18-metre penalty chance, but his kick bounced back off the post.

Irish struggled to rediscover their early rhythm, despite Flutey's prompting, and Franze, who had earlier botched a point-blank drop-goal attempt, wasted a glorious opportunity by failing to find unmarked team-mates Armitage and Topsy Ojo outside him.

But Worcester were finally undone after a series of scrums five metres out when Flutey cleverly worked Geraghty through a gap before slotting the conversion to secure a 12-7 interval lead.

Irish boss Brian Smith made a double substitution for the second period, sending on prop Faan Rautenbach and back-row forward Juan Leguizamon, yet any chance of gaining scrum dominance soon evaporated.

Referee Barnes reverted to uncontested scrums after both Warriors props - Tony Windo and Tevita Taumoepeau - went off in quick succession, which infuriated Irish's animated touchline staff.

Flutey and Delport threw punches during a dust-up involving several players - indiscipline which saw both players yellow-carded, which in Delport's case translated to red.