The four-time European champions were offered a stern test by their United Rugby Championship rivals, who crossed through John Porch and Salesi Fifita, with Jack Carty kicking 11 points.

However, Lowe’s double and a further score from Hugo Keenan proved enough for Leinster, who take their advantage into next week’s second leg.

Connacht fed off a boisterous home crowd and started the game on the front foot, marching into the Leinster 22m with a series of strong carries.

The visitors looked to have escaped as they turned over possession, but lock Fifita charged down a clearing kick to keep Connacht on the front foot before centre Bundee Aki delayed his pass to Porch perfectly to send his winger over in the corner.

Wonderful hands 🔥

This is how @connachtrugby took the lead 👊#HeinekenChampionsCuppic.twitter.com/2uwGbOHAuA

— Heineken Champions Cup (@ChampionsCup) April 8, 2022

Leinster began to grow into the game as the first half wore on, but they struggled to maintain significant pressure on Connacht’s defence and opted to kick a penalty through fly-half Johnny Sexton on 18 minutes.

Once on the score board, Leinster started clicking through the gears and they would grab their first try of the game four minutes later as Lowe came off his wing to take advantage of a disorganised Connacht defence and race over under the posts.

Sexton added the extras to put Leinster five points clear, and Leinster’s lead would be extended further as Lowe darted over for his second try in four minutes after linking with full-back Keenan.

Connacht fly-half Carty and Sexton exchanged penalties over the remainder of the half, with the former kicking his second in overtime to reduce the deficit to seven points at the break.

Connacht started the second half in the ascendancy, storming into the Leinster 22m and threatening the line, though they would have to settle for three points as Carty slotted a penalty from in front of the posts.

Leinster hit back and put Connacht under immense pressure on their own line – Lowe saw a hat-trick score ruled out by the TMO but the away side continued to win penalties at scrum time, and Keenan eventually found his way over for their third try from close range.

The pressure pays off 😎

Hugo Keenan scores for @LeinsterRugby to extend their lead 🔥#HeinekenChampionsCuppic.twitter.com/9xpKtlnQS9

— Heineken Champions Cup (@ChampionsCup) April 8, 2022

But any Leinster plans to control the contest from then on took a hit as replacement scrum-half Jamison Gibson-Park was sent to the sin bin for a high tackle.

Connacht immediately took advantage of the extra man, setting up camp on the Leinster line before forcing their way over the line through Fifita, Carty’s conversion reducing the deficit to two points.

The hosts went close to taking the lead on 65 minutes as replacement lock Oisin Dowling looked to finish off a fantastic move but lost the ball when attempting to dot down.

It was the same story at the other end moments later as Leinster flanker Caelan Doris knocked forward when grounding, and the two sides remained two points apart heading into the final 10 minutes.

Neither side was able to create a clear try scoring opportunity, though Leinster ensured they would take a five-point lead into next week’s second leg at Aviva Stadium as replacement fly-half Ross Byrne kicked a late penalty.