It took Leinster all of 65 minutes to secure the bonus-point try from Josh van der Flier to guarantee the number one seed for the Heineken Champions Cup knockout stages.

Jimmy O’Brien and Hugo Keenan secured doubles and Gary Ringrose registered the sixth in injury-time in a rattling good contest at Aviva Stadium on Saturday afternoon.

It all began with a period of kick-ball gave way to Keenan’s open field tackle on Finn Russell and a Caelan Doris block, both superseded by Ross Byrne’s immaculate crossfield kick for O’Brien.   

Leinster’s offloading, exemplified by James Ryan to Keenan, was undermined by imperfect handling by Jack Conan and Joe McCarthy.  

Indiscipline at the ruck cost back-to-back penalties which were repaired by stout defence and a clever kick by Jamison Gibson-Park. 

Then, Jamie Osborne’s backdoor pass enabled Ringrose to breeze through the middle and feed O’Brien for the opening try, converted by Byrne in the 16th minute. 

The French had to be clued-in not to lose their way as multiple offloads asked many questions which Wenceslas Lauret had the answer for in an agile turnover. 

Andrew Porter’s side-entry at a maul allowed Russell to find the corner for a 5-metre lineout which Ryan promptly stole. 

Doris had the pace to cover Christian Wade before Jordan Larmour was binned for slapping down Gael Fickou’s pass in the 28th minute.  

The obvious danger of a driving maul from another 5-metre lineout was neutralised by Ryan’s nuisance value for a turnover. 

Racing finally got their act together from a lineout for hooker Janick Tarrit to ground the ball in the 33rd minute.

Leinster narrowed their focus, using the forwards to truck it up the guts, turning down an easy three only for Doris to be pinged for obstruction.

The commitment to play never sagged even though the execution did as a malfunctioning lineout signalled the half-time whistle.  

Finn Russell looked to ease Racing in front from a scrum penalty, the shot falling short. The French were stalled by Joe McCarthy’s timing of the tackle before Warrick Gelant rescued a turnover.

Scotland out-half Russell used a lucky bounce of the ball to snipe between defenders, accelerate and whip a ball wide to Wade for a terrific try for 10-7 in the 48th minute. 

The home side was suddenly behind and the reaction was immediate, Larmour contesting and van der Flier flying onto a loose ball. 

Byrne took the invitation to shoot into a gap and fizz a left-to-right pass for Dan Sheehan to set up the try for Keenan in the 53rd minute. 

A tremendous 50-22 kick by full-back Gellant catapulted Racing into an attacking position which was repelled.

Leinster were just not quite on their game, unable to finish off sweeping movements, Ryan caught for a side entry into a ruck.     

Larmour was released down the right and Jack Conan was prominent in taking the ball on before O’Brien couldn’t connect with Ringrose.    

Again, Leinster refused to take three points, going to the corner where a slick ball to Conan at the front was driven at speed to the whitewash for van der Flier to claim the try in the 66th minute.

High pressure from Leinster forced the French into a retreat where Conan pounced for a penalty on the floor.    

Quickly, Conan was the instigator from a meaty carry. O’Brien sliced Racing open and the wing offloaded for Keenan to secure the bonus-point, Byrne converting for 24-10 in the 70th minute.   

Porter was the next man up to grab a penalty over the ball. When a Leinster move faltered,  Ringrose hacked the ball ahead, immaculately picked it at speed and put O’Brien in for the fifth try in the 74th minute.

Unwilling to kick the ball dead, Cian Healy bombed into the clear and a sustained attack ended with Ringrose diving in at the left corner for Harry Byrne to convert.