European Cup Pool Four: Soon after the final whistle, the Munster players returned from the dressing-room for a few fleeting moments to accept and return the applause from a travelling support which must have numbered over 20,000.

But it was a ritualistic gesture, conducted sheepishly, and more in recognition of the fans' performance than their own.

"If you'd just come from our dressing-room now you'd swear we'd lost," admitted Frankie Sheahan later. And this, after an Irish win in Twickenham of all places, to secure Munster's seventh Heineken European Cup quarter-final place in succession. Another sign of Irish rugby's progress, in a curious sort of way.

In truth it hadn't been anything like the occasion or the match we might reasonably have anticipated. At less than half full, a huge stadium like Twickenham is still going to be half empty, even with the Red Army in attendance, and Munster's performance betrayed real and rare signs of acute nervousness which long before the end permeated through to the crowd.

This error-strewn performance was a fitting postscript to what has probably been Munster's least convincing pool campaign of the last seven. Yet the try tally of a dozen, easily the lowest at this juncture in the last seven years, is a barometer of their ills. Try scoring has never come easily for Munster, but this season it has even been harder.

As with the opening win over Harlequins and last week's win at home to the Ospreys, Munster were not able to add to two first-half tries. That has been the key difference between this season and last.

Nor was the problem here a shortage of ball. They ruled supreme in the air, lending credence to coach Mark Evans' assertion that they have the best lineout in Europe, and they scrummaged well - cleverly if perhaps not legally getting a slight shunt after the hit and before Peter Stringer's put-in.

However, the only streak of typical ruthlessness so far was against Castres, and like some Celtic League wins in December, that came almost exclusively on the back of their rolling maul. Here Harlequins, like the Ospreys, negated it at source, often getting away with a player going to ground before the drive could start.

This was compounded by Munster's poor work at the breakdown, where Harlequins competed wildly, and a litany of forced passes, handling errors and wrong options as the shape of their game broke down which ultimately contributed to at least 14 turnovers.

Ronan O'Gara's absence was immeasurable, not least because of the ripple effect it had on others. Stringer has felt obliged to take on more decision-making in the last two games, and even his famed service suffered here, while outside him some of Burke's handling and tactical kicking was poor. Indeed, when he came on for Quins, Jeremy Staunton was the pick of the three Irish outhalves on view.

Harlequins are mightily effective at the sort of spoiling, negative tactics, which reduced Rob Andrew to apoplexy earlier this season, and the penalty count of 18-8 was testimony to that.

Referee Joel Jutge allowed the breakdown to become a mess. He hardly enforced the hindmost foot rule and must have been unhappy with his own performance.

Yet, even up for this game, this is still the Harlequins side which the Ospreys and Castres, along with several English teams, have put to the sword this season, and Munster's biggest failing was that collectively they didn't get to the breakdown quick enough, in enough numbers or low enough.

It would be easy to point the finger of blame at Denis Leamy as the team's openside but not even Josh Kronfeld in his pomp made it to every breakdown, and all the more so if Leamy himself had just taken the ball up into contact at the previous ruck. On the day, Leamy was Munster's best ball carrier and much else besides.

To recover from the risky, floated cut-out pass which Ugo Monye picked off for a breakaway intercept try, and stem Munster's momentum at the time, as he did, and assume the responsibility to score Munster's second try from a blindside rumble with trademark strength, speaks volumes for the young flanker's mentality.

A special talent, he is having an extraordinary season and, were it a straight form choice between the rich crop of young opensides around, he is possibly in pole position to start the Six Nations as Ireland's openside.

He was also putting massive hits right up until the last minute, while Alan Quinlan too was immense defensively. Anthony Foley had possibly the quietest game of what has been an outstanding season although it transpired afterwards that the Munster skipper had been struggling all week with an undisclosed injury.

Munster missed more first-up tackles than in any other European Cup game to date, with Burke and Mike Mullins notably culpable. Only their scrambling defence and some wrong option taking after clean incisions by Andy Dunne and Gavin Duffy, coupled with two poor penalty misses by Dunne, prevented the first-quarter damage being greater. But it assuredly contributed to the nervousness of their display thereafter.

This despite a confidently worked, patient try wide out by Anthony Horgan after Shaun Payne, easily Munster's best back, Paul O'Connell and Leamy had made inroads. Foley was vindicated in going for the corners rather than take shots at goal leading up to half-time in that Quins were reduced to 14 men and conceded Leamy's try, but after the resumption they opted to make sure of the win first with two penalties by Burke.

It needed a brilliant, one-on-one try-saving tackle by Christian Cullen on the dangerous Monye to ensure some breathing space and by the end, a weary Munster looked as if they had run out of ideas.

SCORING SEQUENCE: 2 mins: Dunne pen, 3-0; 9 mins: Horgan try, Burke con, 3-7; 28 mins: Monye try, Dunne con, 10-7; 40 (+5) mins: Leamy try, 10-12; (half-time: 10-12); 52 mins: Burke pen, 10-15; 67 mins: Burke pen, 10-18.

HARLEQUINS: G Duffy; S Keogh, D James, M Deane, U Monye; A Dunne, O So'oialo; C Jones, A Tiatia, J Dawson, K Rudzki, S Miall, N Easter, T Diprose (capt), L Sherriff. Replacements: R Winters for Rudzki (40 mins), G Dott for Winters (40-48 mins), J Staunton for Dunne (55 mins), T Williams for Duffy (60 mins).

MUNSTER: C Cullen; S Payne, M Mullins, R Henderson, A Horgan; P Burke, P Stringer; M Horan, F Sheahan, J Hayes, D O'Callaghan, P O'Connell, A Quinlan, D Leamy, A Foley (capt), D Leamy. Replacements: G McIlwham for Horan (30-32 mins), J Williams for Foley (73 mins), J Holland for Henderson (84 mins).

Referee: Joel Jutge (France)