Leinster survived a nail-biting conclusion to win the European Champions Cup for a record-equalling fourth time, edging out Racing 92 15-12 in a dour battle at Bilbao’s San Mamés Stadium.

Captain Isa Nacewa landed the match-winning penalty in the 78th minute, but Leo Cullen’s men had to survive a frantic finish at the end of which Racing replacement Remi Tales pushed a drop goal effort wide.

Racing shrugged off injuries to out-halves Dan Carter and Pat Lambie to lead twice during a cagey first half, Teddy Iribaren’s two penalties being cancelled out by a Jonathan Sexton brace on the greasy surface.

The 6-6 scoreline became nine-all and then 12-all as the impressive Iribaren landed four of his five penalty attempts and Sexton finished with three. It was left to the retiring Nacewa to bring Leinster level, before an offside decision against Tales allowed the 35-year-old winger to boot the Blues to their first European title since 2012.

Head coach Cullen said afterwards: “Racing are so aggressive at the ruck and very smart the way they play the game. I thought Teddy Iribaren was outstanding, pinning us back the whole time. They played that territory game and just made it very difficult for us.

“There were times in the first half when we were carrying into heavy traffic and then there’s players on our side of the ball. We just couldn’t get a flow into the game and it was frustrating at times. We didn’t quite execute a couple of things and we were just maybe a little bit off.

“The message was very clear at half-time (at six-all), just stay patient. We couldn’t quite get our noses in front, Racing always had that bit of an edge, in terms of they were always on the right side of that three points. But credit to the players, it’s phenomenal how they dug it out, stayed very composed right to the very end and pushed and pushed and pushed the whole time.”

The former Ireland international added: “It wasn’t pretty at times, it was tough to watch that last 20 minutes. Torturous in many ways. Delighted for the players, it’s great to see them up collecting the trophy because I know how hard they’ve worked to get to that point. We talked yesterday about it seemed a long time ago, 2012, when we last won. The amount of work that’s gone in behind the scenes. An incredible feeling at the end.

“Maybe the fact that it was ugly like that makes it even better. The quarter-final and semi-final (against Saracens and Scarlets) were some very, very good performances from the team, and it was a completely different type of performance today. Maybe that makes it that bit more special, we have to go through the pain watching it! It was tough but credit to the players. I’m delighted for them.”

The unbeaten province, who were red-hot favourites before kick-off, now jointly hold the record for most European Cups won (four) along with Toulouse, while Cullen is the first man to win the tournament as both player and coach.

Nacewa, Sexton, Cian Healy and Devin Toner all collected their fourth winners’ medals following the hard-fought success in northern Spain, joining Cedric Heymans and Frederic Michalak as the most-decorated players in Champions Cup history.

A hamstring injury spoiled Carter’s European swansong, with Tales taking the All Black great’s bench spot. Racing’s injury list already including talismanic skipper Maxime Machenaud (ruptured knee ligaments) and Dimitri Szarzewski (torn bicep).

Lambie’s final lasted just under three minutes, the South African stand-off damaging his knee on an early break which led to scrum half Iribaren’s opening penalty from 45 metres out.

Sexton levelled in the 16th minute following his own loop play with Scott Fardy and a penetrating run on the left wing from Nacewa, but Iribaren, who impressed along with Camille Chat in a composed first quarter from 2016 runners-up Racing, punished a maul infringement for 6-3.

Although struggling to produce quick ruck ball, Leinster had the edge under the high ball through Rob Kearney. Man-of-the-match James Ryan’s infectiously high work-rate launched Leinster forward to win a kickable penalty, only for Sexton’s tap-and-go to end in a relieving breakdown penalty poached by hooker Chat.

Nonetheless, Sexton made no mistake with a 38th-minute effort from the tee, following a deliberate knock-on by Leone Nakarawa who narrowly avoided the sin-bin. With their side back level at six points apiece, the vocal Leinster fans in the 52,282-strong crowd were hoping for a more open second half.

However, defences remained on top during a tense closing 40 minutes. Iribaren’s right boot restored Racing’s lead five minutes after the restart, rewarding a bruising set of carries from his pack. Sexton slipped in his attempts to respond with a difficult 48-metre penalty.

The Ireland number 10 nailed his next effort to square things up again in the 53rd minute, the 2009, 2011 and 2012 champions beginning to find some half-gaps through the direct carrying of Robbie Henshaw and Sean Cronin.

Sexton suffered his second miss from long range, following a James Ryan lineout steal, and as the contest became increasingly scrappy, Iribaren’s only penalty miss of the evening let Dan Leavy off the hook for a high tackle.

Referee Wayne Barnes’ whistle was heard far too often for both sides’ liking, the stop-start fare leading to successful place-kicks from Iribaren (70 minutes) and Nacewa (73) and a dramatic climax to this try-less tie.

Crucially, it was Racing who slipped up when Teddy Thomas was tackled into touch, and Nacewa took full advantage of Tales’ subsequent offside to land a central penalty and claim a very hard-earned victory – Leinster’s ninth of the campaign which matches Saracens’ perfect 2015/16 run.