The unstoppable shifted the immovable. A meeting of the two leading clubs in Europe always threatened to come down to a few moments and two, either side of the interval, decided it in favour of Saracens who came from 10 points down against the holders to secure the Champions Cup for the third time in four years.

The first came four minutes before the break and marked the game’s turning point. Leinster were 10-0 ahead and had a man advantage with Maro Itoje in the sin-bin for two counts of offside as Saracens defended a series of drives near their line. In addition, the Premiership champions had just lost their two props, including Mako Vunipola, to injury. They looked vulnerable and the European champions sensed their moment.

Leinster moved the ball from their own half. The No 8, Jack Conan, took possession in midfield with the dangerous Jordan Larmour, who had caused Saracens more than one moment of anxiety with his pace and deception, lurking to his right. In front of Conan stood Alex Lozowski, the Saracens centre who, had it been a boxing match, would have been a few weights below.

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Lozowski lined up his target and as Conan was contemplating his options he found himself dumped on his back; he appeared to shake his head in disbelief. It brought to mind a tackle by another centre, Scott Gibbs, on the 1997 Lions tour to South Africa when he felled a prop, Os du Randt, an act that shattered the Springboks’ perception of physical superiority.

So it was here. George Kruis followed up Lozowski’s tackle by nailing Johnny Sexton and when Vincent Koch, the replacement prop who made a significant difference when he came on, won a penalty after clamping his hands on the ball, Owen Farrell kicked the three points. The momentum had shifted to Saracens and, instead of playing out time and getting into the dressing room, Leinster went for another score and conceded a penalty.

They soon found themselves defending a lineout in their 22. Saracens drove their way inexorably to the line and while Leinster made every tackle against a team containing so many big forwards, they could not protect the gainline. Even so Saracens could not batter their way over and it was only when Ben Spencer saw space wide on the left and found Farrell that the try came through Sean Maitland.

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That made it 10-10 at the break. The second key moment came six minutes after the restart; Leinster started well after composing themselves in the dressing room. Scott Fardy went close, Tadhg Furlong, the scorer of their try after 32 minutes, knocked on a few metres out and Saracens were scrambling desperately. Leinster had looked to suck in the defence before going wide all match and they had worked an overlap when Garry Ringrose received the ball. He had his co-centre Robbie Henshaw unmarked outside him and a pass to hand would have restored Leinster’s lead.

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In flew Liam Williams. The Lion was playing on the wing but he showed the defensive skill of the full-back he is at international level. He not only tackled Ringrose and prevented him from offloading but immediately got back on his feet and forced a turnover with Kruis. Sarries went downfield; Leinster had breathed their last.

Jackson Wray made a clean break and after Leinster defended their line Richard Barrington claimed he had grounded the ball on a post. The referee, Jérôme Garcès, watched a replay of the incident on a screen that was brought on to the pitch. Leinster’s captain Sexton, knowing Saracens had seized the initiative, asked him to look at a knock-on in the buildup but was shooed away.

Barrington was denied his try but sent to the sin-bin for offside. Farrell kicked the penalty to put Saracens ahead for the first time and they took a grip on the game not even a team as accomplished as Leinster could weaken. The final quarter was a procession, victory sealed by Billy Vunipola who forced his way over the line from a scrum. The try captured the match in a moment, power and persistence prevailing.

Facebook Twitter Pinterest Billy Vunipola forces his way over for the try that ended Leinster’s resistance. Photograph: Billy Stickland/Inpho/Rex/Shutterstock

Vunipola, who was to follow his brother off the field after injuring his left shoulder making the score, had been increasingly influential. Two second-half interceptions crushed Leinster’s comeback attempt and, having started the match in the outside channel as Saracens looked to attack Leinster from wider out, he became the gainline breaker.

Leinster set out to thwart Saracens’ blitz defence by sniping around the fringes of the breakdown or attacking the blind-side but they struggled to recycle the ball quickly enough. They took an early lead with a Sexton penalty and their try followed Itoje’s sin-binning: opting for a scrum under the posts rather than a kick at goal they launched three drives that ended with Furlong scoring.

Then came Lozowski’s tackle. He is one of the smaller units in a team containing the Vunipolas, Will Skelton, Jamie George, Koch and Itoje, but he tackles with the impact of his captain, Brad Barritt. He sums up Saracens, knowing what is expected and how to deliver. It will take a lot to stop them joining Leinster and Toulouse on four European victories next season.