Leeds' relegation from the Guinness Premiership could be confirmed on Sunday after they suffered their 15th defeat of a dismal league campaign against title contenders London Irish.

The Tykes will relinquish top-flight status following five seasons among England's elite if Newcastle collect a minimum three points from their Kingston Park appointment with Premiership leaders Sale Sharks.

Even if the Falcons fail against an under-strength Sale outfit, Leeds can only possibly survive through winning their final two league games - against Gloucester and Newcastle - and hope the Falcons suffer three successive defeats.

Leeds are effectively resigned to life in National League One next term, and they also had skipper Stuart Hooper sent off - he received two yellow cards for punching - despite producing a battling display.

Tykes outscored Irish 4-3 on tries claiming touchdowns by Justin Marshall, Chris Bell, Tom Biggs and Nathan Thomas to collect two bonus points, yet the Exiles always looked capable of cutting loose as they moved second - their all-time highest Premiership position - above play-off rivals Wasps and Leicester.

Flanker Declan Danaher, centre Nils Mordt and full-back Delon Armitage scored tries for Irish, with fly-half Riki Flutey's 13-point contribution keeping Leeds at bay.

Irish though, will also reflect on a series of wasted chances that cost them an extra point and undoubtedly earned them a dressing room rebuke from rugby director Brian Smith.

Irish saw their quest for the play-offs boosted by centre Mike Catt and Samoan wing Sailosi Tagicakibau both returning to action after they missed last weekend's narrow victory over Worcester because of injuries.

Leeds, meanwhile, arrived in Reading after going almost five months without an away league win and knowing their Premiership fate could be sealed during the next 24 hours.

Irish made all the early running, but blew a glorious chance to open their account inside three minutes when lock Kieran Roche's wayward pass evaded an unmarked Olivier Magne and Leeds escaped.

Tykes' former All Blacks scrum-half Marshall then had a pass intercepted just inside the Irish half, and only frantic defence kept out the home side before Flutey booted them ahead through a ninth-minute penalty.

Irish continued breaching Leeds' defensive line almost at will, but poor finishing thwarted the Exiles, with Tagicakibau failing to take advantage of an interception 70 metres out as Bell hauled him down when a try looked certain.

Leeds though, cracked as a one-sided opening quarter neared its conclusion when Irish relentlessly went through several phases of attacking play and created enough space for Danaher to collect Flutey's perfectly-placed crosskick without a Tykes defender in sight.

Flutey added the touchline conversion, and although Marshall provided a glimmer of hope for long-suffering Leeds fans when he touched down three minutes later, normal service was quickly resumed.

Leeds just could not cope with Irish's pace and invention as slick approach work from Flutey and hooker Robbie Russell worked Mordt over for a quality try.

But Mordt's role in the action ended eight minutes before the break when he fell awkwardly and was helped off nursing what appeared to be a knee injury, which meant England Under-21 international Shane Geraghty joining Catt in midfield.

Irish continued pressing as the interval approached, yet referee Chris White suddenly became the game's dominant figure, brandishing yellow cards to Magne and Hooper following an exchange of blows.

Magne and Hooper almost squared up to each other again as they left the field, before a contentious penalty awarded to Leeds barely a minute later prompted an animated response in White's direction from frustrated Irish captain Catt.

Smith made a double half-time substitution, sending on prop Richard Skuse for Faan Rautenbach and hooker David Paice instead of Russell as his team targeted two more tries in pursuit of a potential winning bonus point.

But it was Leeds who came out firing, and they narrowed the gap to two points when Bell used his strength from close range to claim a try that De Marigny converted.

If Irish needed a wake-up call then it had certainly arrived, and an error by Biggs inside his own 22 gave them an attacking platform only for Magne to see a try ruled out because of a forward pass before Flutey slotted an easy penalty.

Another Flutey penalty six minutes later eased Irish further ahead, but they were rocked on their heels midway through the half as Leeds responded to Hooper's dismissal by fashioning a breakaway try for Biggs.

Armitage's try then sealed the deal for Irish - and left Leeds reflecting on yet another loss, despite Thomas' injury time score which secured two bonus points.