Former European Cup finalists Munster face the daunting prospect of travelling away from home in this season's knockout stages after struggling to beat Harlequins at Twickenham.

A record 33,883 crowd watched the final Pool Four game switched from The Stoop to accommodate the red and white army of travelling Irish fans.

Many will have gone home disappointed after Harlequins mounted an outstanding rearguard action that prevented Munster from adding to their two first-half tries.

Wing Anthony Horgan and outstanding flanker Denis Leamy both touched down before the break with Harlequins old boy Paul Burke adding a conversion and two penalties.

But despite winning the bulk of the possession they made too many unforced errors - like the one by Leamy that gifted Ugo Monye an interception try, while Andy Dunne slotted a conversion and penalty to keep Quins in touch.

The win means Munster top the pool with 22 points but that might not be enough after tomorrow's games to guarantee a home quarter-final as one of the top four pool winners.

Nobody enjoys playing at on their own turf more than the side who have never suffered a European Cup defeat at Thomond Park. Their away record suffers by comparison.

Mind you, they brought so many fans with them today that you could have mistaken Twickenham for Limerick as The Fields Of Athenry echoed around the stadium.

The Munster supporters comfortably outnumbered the home ones in the 33,883 crowd that set a new record attendance for a European Cup pool game, surpassing the previous best of 23,463 who watched Leinster play Cardiff at Lansdowne Road last season.

The visitors did not have it all their own way, though, as Quins dug in and only trailed 12-10 at the interval after some dogged defensive work.

Dunne's second minute penalty got them on the board and they might have led at the break but for his two costly misses after 10 and 12 minutes.

Munster's forwards, though, produced a steady stream of possession and they battered away at the line before Alan Quinlan's agile handling to send Horgan over on the left with Burke converting.

But they could not reproduce that continuity consistently and the frustration contributed to the risky pass from Leamy that Monye intercepted just before the half-hour.

The England Sevens flier anticipated the move, broke a tackle and scorched 80 metres to score under the posts and make Dunne's conversion a formality.

Quins were on the back foot after that for long spells as Munster turned down kickable penalty chances in their search for a try before the break.

They did so against 10 men after hooker Ace Tiatia was sin-binned by French referee Joel Jutge for coming round the wrong side of a ruck.

Munster took advantage in stoppage time when they surged towards the left-hand corner with Leamy making up for his earlier error by driving through Monye to score.

Burke added a penalty 10 minutes into the second-half as it became apparent that just winning the game was going to be hard enough for the 2000 and 2002 finalists.

He added another after 66 minutes from 40 metres to open up an eight-point gap but that was the last score as both sides made mistakes trying to force the pace in the closing stages.

If anything, Harlequins finished more strongly, something that will cheer coach Mark Evans as he contemplates a long relegation battle ahead in the Zurich Premiership.