The electric centre was one of nine of the province's 14 World Cup players in the XV for the visit of Benetton on Saturday for this European opener.

They were joined by a tenth when Robbie Henshaw was added to the bench in place of Rory O'Loughlin who had himself slotted in at 12 for Joe Tomane.

The former Wallaby had damaged a hamstring in Friday's captain's run.

Henshaw came on in the final quarter and head coach Leo Cullen will be relieved to have seen him and the likes of Jonathan Sexton and James Ryan clock in for their first club shifts of the season. This was decent from Leinster considering the turnover in personnel required.

Ringrose was irresistible throughout this relatively entertaining affair, which was closer than the scoreline suggested.

Leinster had many threats with ball in hand as they cut through the opposing defence but the Ireland midfielder was head and shoulders above them all.

It was far from a perfect performance from the four-time champions who have made no secret of their intent in claiming that fifth star this season but it was a game which introduced fresh blood to the European scene while reintegrating so many of the star names.

Ronan Kelleher plundered a try on his maiden appearance in the competition.

Ringrose needed just five minutes to get the ball rolling when finishing off a move that owed its instigation to his own punch through the defensive cover way back on the halfway line. It was a reassuring sign of things to come.

Benetton had claimed a win and a draw from their last two visits to Dublin in the PRO14. The game between the sides in Italy earlier this season had resulted in a tight five-point win for the Irish province but this was a higher level again given it was Europe and both sides were stronger.

The visitors showed their intent immediately after going behind when, with an easily kickable three points abegging, Ian Keatley kicked to touch. Their reward was five points that would stretch to seven thanks to a Dean Budd touch down off a lineout and maul.

It was an impressive statement.

Ringrose struck back on 15 minutes with his second score, converted this time by Jonathan Sexton, but a game that was beginning to warm up nicely was interrupted for a lengthy period midway through the half when Caelan Doris required treatment and eventually went off for a HIA.

Though competitive and dogged, Benetton were conceding penalties virtually every time Leinster built up some steam at this point and loosehead prop Nicola Quaglio was sent to the sin bin for one tackle on Kelleher coming up to the half-hour.

Just as worrying for the Italians was the fact that the offence occurred deep in their '22' and Leinster made full use of that with Kelleher trundling over for his seventh try in just six games. Not bad. This guy seems to be everything we heard he was.

Keatley couldn't eat into the 19-7 deficit with a penalty that fell short from near the halfway just before the interval and Leinster had the bonus point secured within minutes of the restart with a break and a finish from Sexton and an unselfish feed from Josh van der Flier.

Game over? Not quite.

Benetton hadn't done a whole lot wrong to be 19 points adrift and they hit back again, this time with a converted try from hooker Hame Faiva with a half an hour still to go.

That was only the start. The next dozen minutes was played almost exclusively in and around the home '22'.

The chants of 'Leinster, Leinster' from the 15,080 crowd must have been music to the ears of the visitors as they pummelled the blue line, but a pair of handling errors and some superb defensive work ultimately held them out at a time when another try would have made things interesting.

Ringrose's third score came with 12 minutes to go and that was that until winger Luca Sperandio bagged a deserved third try for Kieran Crowley's well-drilled side and one which may well cause Lyon and and Northampton some problems in the weeks leading up to Christmas.

Leinster: J Larmour, D Kearney, G Ringrose, R O'Loughlin, J Lowe, J Sexton, L McGrath; C Healy, R Kelleher, A Porter, D Toner, J Ryan, R Ruddock, J van der Flier, C Doris.

Replacements: M Deegan for Doris (HIA, 16); J Tracy for Kelleher, P Dooley for Healy, M Bent for Porter and R Byrne for Sexton (all 57); S Fardy for Ruddock and R Henshaw for O'Loughlin (both 63); J Gibson-Park for McGrath (70).

Benetton: J Hayward, A Esposito, N Brex, A Sgarbi, L Sperandio, Keatley; D Duvenage, N Quaglio, H Faiva, M Riccioni, I Herbst, D Budd, G Pettinelli, B Steyn, N Manu.

Replacements: F Zani for Sperandio (28-39) and for Quaglio (57); T Pasquali for Riccioni (HIA, 29-39); M Fuser for Budd and T Halafihi for Manu (both HT); E Makelara for Faiva and T Allan for Sgarbi (both 52); T Tibaldi for Duvenage (59); A Scarbi for Esposito (blood, 64-72); M Lazzaroni for Herbst (66); H Faiva for Makelara (73).

Referee: P Brousset (France).