Wasps endured a torrid start to their Guinness Premiership title defence with London Irish emerging easy winners from the season's curtain-raiser at Twickenham.

The champions' frailties at the lineout were exposed by Chris Hala'ufia and Richard Thorpe who crossed for Irish after capitalising on errors at the set-piece.

Ian McGeechan's side are traditionally slow starters - last season they left their revival later than ever - and they were off the pace and shapeless in attack.

Irish were left reeling after finishing seventh last term, a position which meant they missed out on qualification for the Heineken Cup, but their rout at Twickenham was an impressive declaration of intent.

They were a far more threatening side, showing a creative spark in attack matched by a tigerish work ethic in the loose which left Wasps living off scraps.

Australian full-back Peter Hewat finished the afternoon with 16 points, successfully completing every kick at goal, and his haul ultimately proved the deciding factor.

Final-quarter tries from Tom Rees and Eoin Reddan gave the score respectability but Hewat's boot meant the outcome was never in doubt.

The Experimental Law Variations have been the main talking point in the build-up to the season and one of the new rules was in evidence as Wasps paid the price for dropping numbers at the lineout.

They used two less players in the sixth-minute set-piece and looked on in horror as Richard Birkett's attempted catch deflected into the hands of Hala'ufia who burrowed over from close range.

But the Tongan number eight was quickly transformed from hero to villain when he was caught tripping Reddan at a free-kick and was dispatched to the sin bin.

Hewat slotted a penalty to add to his earlier conversion, nudging Irish 10-0 ahead, after showing a neat side-step to open Wasps' defence.

Conditions were slippery with a fresh downpour making play even trickier as England number eight James Haskell dropped a quick tap free-kick to emphasise the point.

Player coach Mike Catt, starting at fly-half in place of the injured Shane Geraghty, showed smart reactions to set up a chance for Topsy Ojo but the England winger ran out of space.

Irish maintained the pressure and were rewarded with another Hewat penalty but soon breathed a sigh of relief when Riki Flutey dropped the ball just short of the line after dancing through two tackles.

Poor hands were also responsible as a daring Exiles breakout from their own 22 ended inches short of Wasps' whitewash with Sailosi Tagicakibau guilty of taking the wrong option.

The champions' problems at the lineout proved costly once again in the 54th minute when Thorpe came up with the ball before swatting aside a poor tackle from Tom Voyce to cross.

Rees got Wasps off the mark as the match entered the final quarter, showing initiative to scamper through a static defence.

But two rapid penalties from Hewat put the result beyond doubt, despite a late Reddan try which saw the Ireland scrum-half capitalise on a slip by Catt.