It was, from the outset, one of those nail-biting European encounters, played in front of nearly 50,000.
If it lacked a little something of the grand occasion it was because Wembley at half-full can seem more like half-empty, if you get my drift. This was no Munster-Leinster at Croke Park.
So, what was it? Well, it was a great day out for Jonathan Sexton, who took his fill of all Leinster's points. And in general, it had value, something from further afield than the cross-border competition of Europe, something a little more alien.
Whatever the South African group chief executive officer Edward Griffiths and the South African coach Brenda Venter say about their largely South African team of players not constituting a South African club in London, there is something familiarly South African about the way they play. Nothing wrong in that -- they won the ball in forthright style and banged big forwards, like Ernst Joubert, into the midfield and when the running stopped they asked Derick Hougaard to kick down field.
They would have built up a lead had not Hougaard uncharacteristically missed with his first two shots at goal. He crashed a penalty against a post, a miss that stood in contrast to Sexton's first attempt, a long-range penalty that bounced off the crossbar and over. Leinster were not exactly subtle in their own way of playing, perhaps aware of the absence of Brian O'Driscoll in the centre, not that the maestro is necessarily all silk nowadays. Sean O'Brien was their new charger, their gainer of ground against all-comers. He coped ferociously with the demands and demonstrated a piston of a hand-off, a pump-action that could drive a beam engine.
But at least Leinster had a bit of flow to their running patterns. The venerable, and still large, Shane Horgan had some neat touches, especially overhead, and the even larger Nathan Hines did his best to offload before contact. The old second-row then had second thoughts and engaged in the full-on stuff. Again, nothing wrong in that. It's what they go to the gym for.
Saracens scored the only try of the first half, Alex Goode positively dainty in his finish after the forwards had put the defence through the sausage maker close to the line.
Leinster were denied a score of their own, through a similar series of charges, Cian Healy deemed to have been short of the line. His wriggling legs at the bottom of the pile-up suggested that he was conscious of his shortfall.
When Sexton kicked his fifth penalty at the start of the second half Saracens rang the changes in their axis around 8, 9 and 10, the change of Hougaard enforced when he was injured in a clash with Luke Fitzgerald who also departed.
There was not time to see if the new formation would alter the structure of the home team's attacks before they were split apart in defence. From a lineout a simple overlap was created by rapid release at a ruck and the arrival of Rob Kearney in the line. The small space afforded to Isa Nacewa suddenly expanded with a fine hand-off of his own design and a deft inside ball to Fitzgerald's replacement, Fergus McFadden, opened the path fully for Sexton. The conversion of his own try gave him all 22 of the visitors' points.
With Hougaard away, somebody had to lead the way back. Up stepped Goode, with two penalties, the second of which went sailing over from distance as if through the thin air over Pretoria. The sense of comeback grew when Richard Strauss was sent to the sin-bin for preventing release at the breakdown.
The only problem for the home team's indomitability was that from the restart they obstructed in front of the catcher and Sexton took his chance to claim a quarter-century of points for himself. They were in the realm of denying Saracens even a losing bonus point.
A fine catch by replacement Noah Cato almost immediately gave Goode the opportunity to drag them back into the zone of minimum achievement. The full-back calmly reduced the arrears to five points, and play settled deep into the visitors' half.
Leinster conceded their seventh penalty of the second half -- against Saracens' two - and Goode narrowed the gap to two points, with five and a half minutes left on the clock. One of those was used up trying to reach the halfway line, but at least the put-in was retained at the scrummage.
Then we had a little stoppage for a blood smear. Christophe Berdos was adding a little touch of drama to the final scene.
With just over two minutes remaining, Saracens crossed halfway, only to go back. Leinster defended that 50m line as if were the point of no return.
Only in overtime did Saracens cross the 10m line. A full minute later they were back in their own half and the victors of two seasons ago were celebrating a rare victory away from home.
Scorers -- Saracens: Goode try 4 pens; Hougaard 2 pens. Lenister: Sexton try, 6 pens, con
Saracens: Goode; Strettle, Farrell (Ratuvou 59), Barritt, Wyles; Hougaard (Cato 47), Wigglesworth (De Kock 47); Carstens, Brits, Nieto, Borthwick (capt), Botha (Smith 61), Burger, Saull, Joubert (K Brown)
Leinster: Kearney; Horgan, Fitzgerald (McFadden 47), D'Arcy, Nacewa; Sexton, Reddan (Boss 57); Healy (Van der Merwe 61), Strauss, Ross (Shawe 76), Hines, Toner (Cullen 70), O'Brien, Jennings, Heaslip (capt)