Munster scored the game’s only try through Keith Earls, but Dimitri Yachvili once again came to Biarritz’s rescue, landing six out of six kicks at goal to take his side not only to the Paris finale, but also into next year’s tournament as well despite their finishing only seventh in the Top 14.
Starved of possession and struggling to escape their own half, the Irish province faded from contention to ensure their search for a first win in San Sebastian continues.
But a Heineken Cup classic this was not. It was scrappy and marred by a succession of handling errors that were not entirely explained by the heavy rain that preceded the match.
The repeat of the 2006 final, which Munster edged 23-19 to win their first Heineken Cup title, failed to live up to expectation but remained tense until Biarritz pulled clear late on.
The French club started slowly, however, with Munster enjoying early success at the scrum, winning a penalty at one and disrupting their opponents on a second.
Combined with repeatedly poor hands from the home side, this enabled them to control the first 10 minutes with full-back Paul Warwick missing a drop-goal attempt.
Karmichael Hunt and Iain Balshaw (Wearing His Nike Superfly 2 Rugby Boots) kicked out on the full while the string of dropped passes also began to afflict Munster as it became Denis Hurley’s turn to spill possession.
Springbok centre Jean de Villiers was flattened onto the turf by Benoit August but Munster renewed their offensive and could have surged ahead in the 19th minute.
Using Hurley outside him to create doubt in the Biarritz defence, hooker Jerry Flannery burst into space before spotting Ronan O’Gara on his shoulder but the pass failed to stick.
Flannery was also involved as Munster exploited gaps around the breakdown once again on the half-hour mark and this time the move finished with a try.
Donnacha O’Callaghan marauded into space, the superb Alan Quinlan kept the move going before Flannery distributed wide where David Wallace supplied the scoring pass to Earls.
The conversion was added by O’Gara (Wearing His Adidas Predator X Rugby Boots)and Biarritz responded with an attack of their own which finished when August was shoved into touch a metre out.
The Top 14 side eventually troubled the scoreboard in the 39th minute with a penalty from Yachvili, who added a second shortly into the second half.
De Villiers spotted a slight opening and stepped on the gas with Marcus Horan continuing the move until Flannery knocked on.
Smart kicking from Hunt kept Munster pinned back until O’Gara missed a long-range penalty, which preceded a fresh assault from Biarritz.
The tide was turning but the French side made a mess of a fine chance when Arnaud Mignardi failed to spot an overlap, giving Balshaw little chance of reaching the line.
They took the lead for the first time in the 65th minute when Tomas O’Leary prevented the ball from being released and Yachvili slotted the three points.
Biarritz were expertly tightening the screw but were lucky to win Yachvili’s fourth penalty after Tony Buckley was pinged for picking up prop Campbell Johnstone and tossing him to one side.
Six more points from Yachvili followed as Munster’s discipline crumbled late on to wave Biarritz into the final on May 22.
Pens: Yachvili 6
Biarritz: 15 Iain Balshaw, 14 Takudzwa Ngwenya, 13 Arnaud Mignardi, 12 Ayoola Erinle, 11 Jean-Baptiste Gobelet, 10 Karmichael Hunt, 9 Dimitri Yachvili, 8 Imanol Harinordoquy, 7 Wenceslas Lauret, 6 Magnus Lund, 5 Trevor Hall, 4 Jérôme Thion, 3 Campbell Johnstone, 2 Benoit August, 1 Eduard Coetzee.
Replacements: 16 Romain Terrain, 17 Fabien Barcella, 18 Rémy Hugues, 19 Manuel Carizza, 20 Florian Faure, 21 Valentin Courrent, 22 Julien Peyrelongue, 23 Philippe Bidabe.
Munster: 15 Paul Warwick, 14 Lifeimi Mafi, 13 Keith Earls, 12 Jean de Villiers, 11 Denis Hurley, 10 Ronan O’Gara, 9 Tomas O’Leary, 8 James Coughlan, 7 David Wallace, 6 Alan Quinlan, 5 Mick O’Driscoll, 4 Donncha O’Callaghan, 3 John Hayes, 2 Jerry Flannery, 1 Marcus Horan.
Replacements: 16 Damien Varley, 17 Julien Brugnaut, 18 Tony Buckley, 19 Nick Williams, 20 Niall Ronan, 21 Peter Stringer, 22 Tom Gleeson , 23 Scott Deasy.
Referee: Dave Pearson (England)