The Irish heavyweights went into the match at Stade de Geneve with a perfect four-from-four record, with Bourgoin playing for pride after four straight losses, but the French club led 15-13 after 30 minutes of an entertaining match.

Tries to back-rower Julien Bonnaire and centre Guillaume Bousses stunned Munster, who replied with a try in the corner from prop Marcus Horan before referee Malcolm Changleng earned the wrath of the crowd in the 36th minute.

With Munster’s pack driving towards the line, Changleng adjudged that back-rower Brice Monzeglio dragged down the maul illegally. He awarded a penalty try and sent Monzeglio to the sin-bin to give the Irish side a 20-15 lead at halftime. They could have been behind when Bousses dotted down late in the half, but he was ruled to have pushed Ronan O’Gara out of the road in the race for the ball.

French fans in the 16,000-strong crowd were ecstatic on the hour mark when replacement winger Matthieu Nicolas powered over to level the scores, but Munster edged ahead again with a try to centre Lifeimi Mafi after a Shaun Payne break.

An O’Gara goal gave the champions a 10-point lead, but 19-year-old Nicolas ensured an action-packed final five minutes by scoring his second try near the uprights.

The win takes Munster to the top of Pool 4, and while a rare loss at their Thomond Park fortress against Leicester next weekend would give the Tigers the top spot, Munster will go through as one of the two best runners-up.