Leinster launched their Heineken Champions Cup campaign in fabulous fashion with a half-dozen tries against highly-rated hosts Racing 92 at Le Havre on Saturday afternoon.

Josh van der Flier led the charge with a pair of tries to go beside those of Andrew Porter, Dan Sheehan, Garry Ringrose and Ed Byrne.

The home side’s indiscipline in the early going handed Ross Byrne the chance to pump three quick penalties into the right area of the field.

A smooth lineout from Sheehan to Jason Jenkins ended with Porter driving to the line for Byrne to convert in the fifth minute.

There was an opening to add to the lead only for the next attack to falter, Racing finally moving upfield from Finn Russell’s connection with Francis Saili.

A picture-perfect poach by Caelan Doris at the breakdown put Leinster on the front-foot until Racing countered at the ruck for three turnovers.

Leinster’s set-piece was working well, the scrum squeezing a penalty and the lineout delivering clean ball.Racing’s first shot at goal came when Leinster countered through Jamison Gibson-Park and Caelan Doris went off his feet for Russell to smack over three points for 7-3 in the 26th minute.

The scrum dominance of the front row of Michael Ala’alatoa, Sheehan and Porter was aided by the lineout again, the Leinster maul motoring forward to see Camille Chat binned for pulling it down.

The carries came straight and often from Leinster, Doris, James Ryan and Ala’alatoa all stopped on the gain line before Jason Jenkins lost the ball forward.

The Blues could have started to lose patience, instead staying on point for Gibson-Park to pop to runners, James Lowe getting in behind and the scrum-half whipping a pass over the top for Sheehan to claim a terrific try, Byrne nailing the touchline conversion for 14-3 in the 35th minute.

Then, Leinster stitched together a wonder try built off fine lines of running, an elegant break by Lowe and an exquisite unorthodox give to Garry Ringrose for the third, Byrne converting in the 38th minute.

When Russell orchestrated a devastating surge, Porter’s recovery speed forced an important spill to maintain a 21-3 lead at the break.

Racing had to throw caution to the wind to get back into the game, a bout of kick-ball ending with Jimmy O’Brien keeping the ball and Charlie Ngatai sending Ringrose up the tramline where Max Spring’s tackle saved a try.

Left-wing Lowe’s dexterity in keeping Russell’s kick in play was supplemented by a booming clearance.

The play was swinging from end-to-end, Juan Imhoff going quickly from a lineout earned by a superb 50-22 kick.

The muscular work of centre Ngatai in ripping the ball away was further bolstered by Leinster resilience in contact close to their line.

The long ball tactic by Lowe and Hugo Keenan was followed up by a tremendous chase and block by Ringrose to keep Racing pinned back.

Replacement Ross Molony clutched successive lineouts and Ryan Baird snatched another from Sheehan’s accurate throws to draw penalties from the French.

The close-in drives mounted until out-half Byrne’s pass almost put Lowe in at the left corner. Coherent continuity applied sustained pressure to see Nolann La Garrec binned for a deliberate knock-on.

A clever move from a tap penalty opened up a sliver of space for Josh van der Flier to blast over for the bonus point try, converted by Byrne for 28-3 in the 63rd minute.

Even when Racing breached the first line, Lowe got back to shut down the attack and aggressive frontfoot defence meant the French were driven back.

Leinster’s one-out runners were coming from deep to break the gain line. Ringrose’s quick tap penalty was central to prop Ed Byrne’s drive to the line for Harry Byrne, on for his brother, to convert in the 70th minute.

The game was in safe keeping, but the points-difference took a knock when the skills of Russell and Gael Fickou enabled Christian Wade to punch in a try, converted by Russell.

The opportunism of Ringrose to seize on a loose ball activated an attack in which van der Flier ghosted through a flatfooted defence to bring up the half-dozen, Harry Byrne’s conversion closing the game.