The French also side made it 51 games unbeaten at home with this narrow victory over the defending champions, but the Irish side came away with a bonus point and kept their own hopes of a quarter-final place alive.

Both sides, viewed by many as genuine candidates to win this season's tournament, came into this heavyweight clash unbeaten, having won their opening two games in the Pool.

Neither side really showed their hand in a first-half which resembled a game of chess with both sides probing and prodding for defensive weaknesses and looking to take any points on offer.

The first half was a typically tight affair with Clermont's scrum-half Morgan Parra and Leinster's fly-half Jonathan Sexton exchanged penalties to make it 12-9 to the home side just before the break.

Clermont's Australian fly-half Butch James landed a well taken drop goal with the last kick of the half to stretch the French side's lead to six points to make it 15-9 lead at half-time.

The Irish province clawed themselves back to within three points when he landed his fourth penalty to keep the pressure on Clermont in front of their partisan home crowd at the Stade Marcel Michelin.

Defence proved to be the common denominator between the two sides during an incredibly tight second half and neither side looked like scoring the elusive try in a compelling contest in France.