Two tries from All Black legend, Doug Howlett, helped seal victory for Tony McGahan's men, who can now look forward to a semi-final date with Biarritz in San Sebastien on the May Bank Holiday weekend.

This was the third meeting between the sides this season, each posting a win apiece from Pool One of the competition, but Munster proved the more determined and more clinical side in this quarter-final clash when a packed Thomond Park again acted as the perfect 16th Man.

Ireland international scrum half Tomas O'Leary gave a man of the match performance setting up two crucial second half tries for Springbok centre Jean de Villiers and New Zealander Howlett, and condemn the Saints to their second defeat at Thomond this season.

Despite making a dream start, Munster still trailed the visitors at the break but resumed in determined fashion, dominating possession and territory with skipper Ronan O'Gara dictating affairs with the boot and milking the touchlines tremendously out of hand.

The Reds' pressure game paid dividends as the Saints failed to generate any go-forward ball and only fleetingly threatened the Munster line during the second period.

Munster meant business from the first whistle and earned a penalty inside a minute, which O'Gara converted, and, five minutes later, Paul Warwick cut the Saints' defence to shreds taking a sumptuous pass from Keith Earls to run over. The ground work was done by the forwards, who mauled the ball inside the Saints half before O'Leary distributed wide to Earls.

The visitors, however, didn't lie down and, by the 17th minute, had narrowed the gap to two points thanks to two well-struck penalties from their impressive No 10, Stephen Myler.

The home side's first try arrived in the 23rd minute, when from a ruck near the Saints line, O'Leary fed O'Gara who gave a brilliant cut-out pass to Howlett, allowing the New Zealander spin out of an attempeted Bruce Reihana tackle to touch down.

O'Gara missed his second conversion of a half Munster dominated, but the Saints' spirit was exemplified in a move close to half time that saw Jon Clarke canter over and Myler's conversion gave the English side a surprise 16-13 lead at the break.

All of Munster's experience in this competition was shown int he second period when they battened down the hatches, dominated the opposition up front and finished try-opposrtunities clinically.

The first of the second half arrived in the 53rd minute: O'Leary did brilliantly off a scrum, 15 metres from the line, taking a pop pass from James Coughlan before switching to Jean de Villiers who came steaming through the middle crashing through four Saints players to touchdown.

O'Gara added the extras and, though Myler notched a penalty almost from the restart, Munster re-asserted themsleves and piled on the pressure mainly through O'Gara's masterly boot in open play.

The outhalf added two more penalties in the 58th and 67th minutes before Howlett added the coup de grace in the 76th minute taking a splendid O'Leary pass to dot down in the corner, a score converted by the in-form O'Gara.

Munster: P Warwick, D Howlett, K Earls, J de Villiers, I Dowling, R O'Gara (capt), T O'Leary, M Horan, J Flannery, J Hayes, D O'Callaghan, M O'Driscoll, A Quinlan, D Wallace, J Coughlan Replacements: D Varley, J Brugnaut, T Buckley, M O'Driscoll, N Williams, N Ronan, P Stringer, L Mafi

Northampton Saints: B Foden, C Ashton, J Clarke, J Downey, B Reihana, S Myler, L Dickson, S Tongauiha, D Hartley [capt], E Murray, C Lawes, J Kruger, P Dowson, N Best, R Wilson Replacements: B Sharman, R Dreyer, B Mujati, I Fernandez Lobbe, M Easter, A Dickens, S Geraghty, J Ansbro

Referee: Nigel Owens (Wales)