It turns out you need more than 15,000 people to drown out the noise generated by James Lowe on a rugby pitch.

In the behind-closed-doors season, the Leinster and Ireland wing did his utmost to make up for the lack of noise by whooping and hollering his way through every forced knock-on and penalty won.

Admirable as his support for his team-mates had been in the last year, one season of it was probably enough, and the thoughts of 15,000 supporters soundtracking a live rugby game rather than players and officials was certainly enticing.

Lowe must have seen it as a challenge though, his voice audible over anything in the Aviva Stadium for the first few minutes of Leinster's 40-21 win against Harlequins this evening.

It only took three minutes for the crowd to be able to cheer something meaningful though, Leo Cullen's side pouncing for a try.

A blocked Harlequins kick found it's way to Johnny Sexton on the right touchline, and the captain drew in a defender before popping inside to Chris Cosgrave. The Ireland U20 back was brought to ground on the 22, but Leinster moved it quickly to the far touchline before Conor O'Brien completed the move to score a try.

While it may only have been a pre-season friendly, it was a dream return for O'Brien who last played a game of rugby in February 2020, a long-term hamstring injury followed up by a torn ACL resulting in 19 months on the sidelines.

His partnership with Sexton may be worth monitoring as the new season develops. There was a natural flow to their movements, an understanding of the space one created for the other, manifested in two further gorgeous first-half tries.

The first of those was started and finished by Sexton; his skip pass inside his own half finding Lowe on the far wing, before Lowe's back-door offload landed in the hands of O'Brien. O'Brien couldn't make it to the try-line on his own, but Sexton had been running a hard support line for the best part of 40 metres and took the simplest of passes before dotting down to score.

Just two minutes later the pair combined again, this time Sexton running a loop around O'Brien before the out-half delayed his pass to the onrushing Jamie Osborne, buying the 19-year-old just enough time for him to crash over and score.

Sexton was tuned in off the tee also, slotting four from four in the opening half, seeing Leinster into the break with a 28-7 advantage, Rhys Ruddock having also crossed the line.

It had been a first half that took almost one hour to complete, although not to the fault of any pedantic officiating. Quins centre Andre Esterhuizen was sin-binned on 21 minutes for high tackle on Leinster full-back Chris Cosgrave.

Cosgrave needed lengthy treatment on on the pitch before being stretchered off, his raised thumb to the crowd as he left the pitch drawing a collective exhalation from the supporters.

Pre-season friendlies being pre-season friendlies, the second half was a slow puncture and it was partly caused by Ryan Baird's wonderful 40m burst to the try-line on 45 minutes.

That made it a 33-7 game, and as the benches emptied in the second half, the game plodded along, Joe Marchant and Sam Reilly crossing for a pair of Quins tries, before Liam Turner finished the game off with Leinster's fifth.

If there's one thing the supporters on Lansdowne Road learned tonight though, it's that the 50:22 is a weapon Leinster want to use this season.

On several occasions in the opening half, Leinster targeted the space in behind the Harlequins defence. And they did it effectively, Lowe and Cosgrave both had early sighters come close, before Lowe found his range with a missile of a kick that landed and showed the full possibilities of the new law.

He wasn't the only one, Osborne's attempt three minutes later very nearly gave his side an attacking lineout, but the centre's kick landed literally inches short of the desired 22.

Leinster scorers:

Tries: Conor O'Brien, Johnny Sexton, Rhys Ruddock, Jamie Osborne, Ryan Baird, Liam Turner

Cons: Johnny Sexton 4, Ross Byrne 1

Leinster: Chris Cosgrave; Rob Russell, Jamie Osborne, Conor O'Brien, James Lowe; Johnny Sexton, Luke McGrath; Peter Dooley, Dan Sheehan, Michael Ala'alatoa, Devin Toner, Brian Deeny, Rhys Ruddock, Scott Penny, Max Deegan

Replacements from: Cian Healy, Sean Cronin, James Tracy, Vakh Abdaladze, Ross Molony, Ryan Baird, Martin Moloney, Cormac Foley, Ross Byrne, David Hawkshaw, Liam Turner, Niall Comerford

Harlequins: Tyrone Green; Joe Marchant, Luke Northmore, Andre Esterhuizen, Louis Lynagh; Tommy Allan, Danny Care; Santiago Garcia Botta, Jack Walker, Simon Kerrod, Hugh Tizard, Dino Lamb, Tom Lawday, Jack Kenningham, Alex Dombrandt

Replacements from: Sam Reilly, George Head, Fin Baxter, Will Collier, Craig Trenier, Matas Jurevicius, George Hammond, Luke Wallace, Archie White, Lewis Gjaltema, Will Edwards, Ross Chisholm, Lennox Anyamwu, Huw Jones, Cadan Murley, Nick David