If revenge were the sole spur, then there would hardly be any point in Leinster turning up tonight. Newport still feel aggrieved over what they perceive as a mugging when the sides met in Europe last time out, and no side in Europe can want an Irish scalp more than they.
There's more to it than that though, and Newport's whiff of vengeance is more than matched by the qualities which have seen Leinster win 11 successive games this season and the whiff of a trophy in the final 16 days away.
Nonetheless, if ever a visiting team to Donnybrook ought not to be lacking in motivation, then Newport are surely it. That loss four weeks ago effectively put the kibosh on Newport's qualification hopes while it sent Leinster hurtling through to the quarter-finals.
It's not just that they've been beaten twice by Leinster this season in Europe either. Both Munster and Connacht overcame them in the pool stages of the Celtic League this season, while Munster did the double over them in Europe last season. Six defeats to Irish sides in scarcely over a year.
But they're a seriously good side, riddled with proven internationals and a highly-rated coach. And they've been making optimistic noises before travelling over as well.
"I think we were the better team on both occasions when we played Leinster," reckons Matt Mostyn, "and we were certainly a bit unlucky at home. This is a great opportunity for us to right a few wrongs."
Nor does the Donnybrook experience seem to perturb the Irish winger, even if Leinster are now unbeaten there in 16 games and over two years.
"It's a difficult place to win but I don't think it's as passionate a place to play as Rodney Parade," says Mostyn.
Probably true, too, though that's also liable to be a better rallying call for an all-ticket crowd than anything Leinster can come up with.
Then again, the unrelenting spell of defeats to Irish sides must be generating some doubt in the collective Newport psyche.
Coach Matt Williams concedes that Leinster would have taken the two European wins out of this three-match series inside six weeks with Newport. "But now that we're here I'm not so sure," he says, laughing. "Human nature can be greedy. This is now a one-off. A totally different competition."
Regarding the last meeting, Williams makes the point that Leinster had five set plays in the Newport 22, whereas "they had 18 in ours, which shows you how hard we worked off the ball".
Newport coach Ian McIntosh claims: "We had 22 attacks in their 22 and they only had seven in ours. We've got to make it count."
Not that Newport are likely to have around three times as many attacking platforms as Leinster tonight. Williams also points out that for all the excellence of Leinster's defence this season (just four tries conceded in their last six games), they missed 38 tackles in the Rodney Parade meeting, but by hook or by crook hung in there.
However, as Williams also concedes, where injuries greatly undermined Leinster's training and preparations for the two European meetings - especially amongst his backs - this time no such excuses apply.
Aside from their excellent recycling game and the alacrity with which Shane Howarth attacks the gain line and distributes the ball, Leinster have also struggled to cope with his positional game and the way he leads their defensive line quickly into Leinster's faces. As Williams concedes, Newport shut Leinster down very well last time out and are improving with each match.
But while heroic defence and opportunism is unlikely to suffice this evening, nor is it likely to be needed. Leinster had been in a prolific vein of form which had yielded 39 tries in a run of six games. Significantly, the outside three of Girvan Dempsey, Denis Hickie and Gordon D'Arcy (who've scored 13 tries between them in this competition) are back in harness.
The greater familiarity of three meetings in six weeks suggests tries will be harder to come by, and there might even be an increased risk of frayed tempers. But nothing has happened this season to doubt that Leinster have the defensive resilience and stealthy opportunism to take their winning run to a perfect dozen.
LEINSTER: G Dempsey; D Hickie, B O'Driscoll, S Horgan, G D'Arcy; N Spooner, B O'Meara; R Corrigan (capt), S Byrne, E Byrne, L Cullen, M O'Kelly, E Miller, V Costello, K Gleeson. Replacements: P Coyle, G Hickie, R Casey, T Brennan, B Willis, A Dunne, A Magro.
NEWPORT: M Pini; M Mostyn, A Marinos, J Pritchard, B Breeze; S Howarth, D Burn; R Snow, J Richards, A Garvey, S Raiwalui, I Gough, P Buxton, A Powell, G Gravell. Replacements: C Anthony, P Young, M Voyle, J Powell, M Watkins, J Strange, AN Other.
Referee: S Lander (England)
Previous meetings: (2001-2 EC) Leinster 21 Newport 6, Newport 21 Leinster 26.
Celtic League formguide: Leinster - W W W W W W W. Newport - W L W L L W.
Leading try scorers: Leinster - Girvan Dempsey, Denis Hickie 5 each, Gordon D'Arcy 3. Newport - Ben Breeze, Andy Marinos 2 each.
Leading points scorers: Leinster - Nathan Spooner 57. Newport - Shane Howarth 58.
Forecast: Leinster to win.