One of the many components in the make-up of champion teams is the ability to ride out the odd storm. In front of 14,425 on a miserable winter's day at one of rugby's great locations, Leinster had to battle to stay afloat.
Moreover, their routine in battening down the hatches sometimes let them down. Still, after an often frantic game they were two scores ahead, and safe, when Bath got after them for the last time, opting for a bonus-point penalty from Jackson Willison with the last kick of the game.
It was a slog - one finished without Johnny Sexton, who hobbled off with a damaged calf, and looks a long shot for the return leg next weekend. Furthermore, it was a slog in very difficult conditions, which might not always have been apparent if you were watching this on a screen. The day in England's south-west dawned wet, but just as it looked like clearing up a biblical rainstorm arrived as the players were completing the warm-up. Thereafter showers were intermittent, and handling errors were a constant.
So too was the quality of Bath's defence. Whatever about Europe, where they are still win-less after three rounds, they had hoped victory here might kickstart a domestic season that is falling well short of the target. Had they not blinked a couple of times in the Leinster 22 it would have panned out differently.
"That was Test match intensity out there," Bath captain Charlie Ewels said. "You play at this level and you get four or five opportunities and you have to take them all - not one or two, which is what we did."
Leo Cullen conceded that his side rode their luck. And never more so than when Sean Cronin threw a wildly crooked ball to a lineout, somehow reclaimed by Bath scrum-half Will Chudley only for his partner James Wilson to throw an intercept for Jordan Larmour. Only one way that was going to finish. It gave Leinster a 14-7 lead on 49 minutes.
Bath's Will Chudley is tackled by Luke McGrath and Garry Ringrose of Leinster. Photo: Ramsey Cardy/Sportsfile
Another referee would have gone back for the scrum/lineout but equally another referee could have red-carded Joe Cokanasiga on 64 minutes after he caught Luke McGrath head-high when following up a box-kick. Referee Mathieu Raynal saw it only as a penalty. So it goes. Cullen had no complaints either way.
"The game was limited in terms of quality because of the conditions but we've got a win away from home," he said. "There's a lot of growth for us. We talked about the challenge for us trying to reintegrate players and getting them back together. It's tough, especially when you travel away from home against a team that is highly motivated.
"There's a hell of a lot of things we can get better at. I thought we lacked that little bit of sharpness in the first 20/30 minutes of the game and Bath got a good few turnovers in that area (breakdown) and towards the end. We were a little bit slow into that space - we know some of the threats they have so everyone is well aware of Francois Louw and [Sam] Underhill. They have other players as well but those two in particular."
Despite the length of time it took them to get to the pitch of the game - something the sizeable travelling support didn't struggle with, even without the 1,500 flags which were reportedly confiscated before the game on healthy and safety grounds - Leinster might still have gone in with their noses in front at the break. The first half finished with them camped deep in the Bath 22 and putting good pressure on the home defence only for Louw to poach from Garry Ringrose five metres from the line.
For Bath to have trailed at that point would have weighed heavily on them given the rhythm of the game for most of the first 40. When Leinster had responded earlier it was with impressive efficiency. They were trailing to a Henry Thomas try when at last they won a big turnover - Devin Toner and Leavy relieved Louw of the ball on the deck and Noel Reid knocked it in behind. Once they established a position in the Bath 22 they forced a penalty, knocked it to touch, and then engineered the perfect maul off a Rhys Ruddock take at the lineout. Cronin was in the box seat quickly and it always looked like having a positive finish for the champions.
That was on 29 minutes, a long time for Leinster to wait for a score against anybody. They would have gone ahead on 11 minutes if Sexton hadn't seen a handy enough penalty come back off the upright.
So 7-7 was fair enough at the break but twice in the third quarter Bath were turned over in the Leinster 22. And it cost them. Ross Byrne added a penalty for 17-7 before Bath's bonus point kick at the death.
Scorers - Bath: Thomas try, Willison pen, Wilson con; Leinster: Cronin, Larmour try each; Sexton 2 cons, Byrne pen
Jordan Larmour of Leinster goes over to score his side's second try during against Bath. Photo: Ramsey Cardy/Sportsfile
Bath: J Wilson; S Rokoduguni, J Willison, J Roberts (C Vuna 65), J Cokanasiga (A Davies 80); J Wilson, W Chudley (K Fotuali'i 73); N Catt (J van Rooyen 58), T Dunn (J Walker 65), H Thomas (M Lahiff 69), D Attwood (E Stooke 58), C Ewels (capt) (M Garvey 69), T Ellis, F Louw, S Underhill.
Leinster: R Kearney; J Larmour, G Ringrose, N Reid (R Byrne 70), J Lowe; J Sexton (R O'Loughlin 76), L McGrath (J Gibson-Park 66); C Healy (E Byrne 64), S Cronin (J Tracey 64), T Furlong (A Porter 64), D Toner (R Molony 78), J Ryan, R Ruddock, D Leavy (J Conan 54), J van der Flier.