Wesley Fofana thought he had won it for the hosts with more than 78 minutes gone but television replays showed the star centre had dropped the ball over the try line, much to the frustration of a truly incredible Clermont support.

Even after Leinster won the resulting scrum five metres from their own line, Clermont somehow earned another shot at glory as the clock ticked towards the red. But with three points for a penalty not enough to win it for Clermont, their final surge to their tryline ended in disappointment as they infringed at ruck time and Leinster breathed a huge sigh of relief.

Cian Healy's try moments after half time proved decisive, with Jonathan Sexton kicking 11 points and Heineken Man of the Match Rob Kearney slotting a monster drop goal.

All of Clermont's points came from the boot of Brock James, with four first-half penalties handing the semi-final final debutants a 12-6 lead at the break. But James could only add one more successful strike in the second period as Clermont fell agonisingly short of trip to London next month.

Sexton opened the scoring with a simple penalty after seven minutes as Leinster started brightly in Bordeaux. Isa Nacewa burst through the first line of defence out wide on the right, Clermont were caught offside and Sexton slotted home from the 22 after referee Wayne Barnes had initially played advantage.

James pushed an optimistic 55-metre drop goal wide of the right post on nine minutes but Leinster continued to enjoy the better of the opening stages and Nacewa was heavily involved again just moments after opposite number Julien Malzieu was forced off with an injury. The Fijian wing caught Kearney's beautiful long pass in full flight before chipping ahead, only for Sitiveni Sivivatu to win the chase to the loose ball.

Clermont levelled affairs thanks to James' first strike on 17 minutes and a second success from the Australian playmaker moved them 6-3 in front just past the half hour.

Sexton made it all square six minutes before half-time but it was Clermont who had started to dominate despite being forced into a substantial reshuffle in their back division. With Lee Byrne joining Malzieu in walking off injured, Clermont brought Regan King into the centre and Jean-Marcel Buttin on at full back, with skipper Aurelien Rougerie moving to the right wing and Sivivatu switching to the left.

Clermont were rewarded with two further penalties from James, who was quickly forgetting his nightmare day with the boot when these two teams met in the quarter-finals in Dublin two years ago.

The second of those, and the fourth in total, arrived on the stroke of half time, leaving Clermont with a 12-6 lead at the break.

But whereas it was the French side who had the momentum heading into the interval, Leinster undoubtedly picked up the pace straight after the interval.

Leinster enjoyed the perfect start to the second half as they caught Clermont napping less than two minutes after the interval. Big bursts from Isaac Boss and Kearney sent Healy cruising over for the game's first and only try, sending the Clermont crowd eerily quiet.

Sexton added the extras from halfway between the posts and the touchline on his favoured left side to hand Leinster a 13-12 lead before Kearney made it 10 points in six minutes with a brilliantly-struck long-range drop.

Clermont refused to buckle, though, and they could have been back in front by the 53-minute mark. Instead they were at least within a point as James fluffed his first penalty of the half but nailed his second to make it 15-16.

Sexton edged Leinster four points clear on 62 minutes with an assured penalty of his own but controversy surrounded his next attempt with 10 minutes left to play. The assistant referees signalled his kick had sailed just wide but a lack of certainty persuaded Barnes to seek confirmation from the TMO. The entire stadium held its breath but when the call came back it heralded the answer that the majority of the crowd were looking for - no score.

It made no difference to the end result, though, as Clermont struggled to get out of their own half until that momentous final five minutes.

Only inches eventually separated Clermont from glory and Leinster from desolation as Fofana made his fateful stretch for the line but it matters not as far as the reigning champions are concerned: their Heineken Cup hopes remain alive while Clermont's are dead and buried for another year at least.