OLD school at the Sportsground as the weather turned and Leinster had to stick it out to maintain their winning start to the season.
Leo Cullen's side romped to victory at the RDS last Saturday by scoring eight tries against the Sharks.
That game had 13 tries in total to feast on while this one had just the one. For Leinster, that was enough.
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But on a miserable night in Galway, Cormac Foley's early converted try and Ross Byrne's late penalty got it done for the visitors as Leinster emulated what Munster achieved twice in 2004 when they kept Connacht scoreless.
This was an interpro of scarce quality and many errors, punctuated by a series of turnover penalties as both sides struggled for consistency.
Still, with seven points between the sides from the third minute up to three minutes from the end, it was very much in the balance.
Then came Byrne's successful kick between the posts in Connacht's 22 after Josh van der Flier's break saw Niall Murray sin-binned for killing Leinster ball.
Baying Connacht fans in the 6,887 crowd vehemently disagreed with ref Frank Murphy's interpretation, insisting that Caolin Blade had been taken out in the ruck to allow van der Flier to run clear.
The decision stood and that was the game.
Connacht came into the fixture buoyant on the back of their first win of the season on their new 4G pitch against Munster.
However it was the visitors who got the start they wanted.
John Porch's penalty concession was ruthlessly punished as Byrne kicked for the corner.
Leinster's maul did its thing before van der Flier sent Cormac Foley over. Byrne nailed the tough conversion.
The Blues threatened to steam comfortably but then failed to score from another close-in lineout.
Encouraged, Connacht came right back into it but a promising foray into their rivals' 22 came to nothing when Byron Halston knocked on.
At the other end, another Leinster line-out maul was held up over the try-line - then the westerners then blew a golden opportunity.
Peter Dooley won a turnover penalty on his former team-mate Byrne and Jack Carty kicked to the corner.
Connacht rumbled towards the posts and when young scrum-half Colm Reilly looked to find Mack Hansen in acres of space, only to miss the Ireland winger and find touch.
That was a costly miss, and there were more to follow before the break.
Byrne missed a long range penalty for the visitors and, as the clock ticked into the red, Connacht twice mauled right to the Leinster line - but they couldn't get the job done.
Jack Conan and Tadhg Furlong, making his season debut, didn't return for the second half for Leinster.
Connacht started the second half brightly enough but a midfield arm-wrestle ensued until Byrne was handed another three point chance when he himself was tackled off the ball by Murray in the 56th minute.
The usually accurate out-half was off-target again and back came Connacht, a Hansen steal setting up another Carty penalty and another line-out platform deep into Leinster's 22.
It was wasted and, ultimately, Connacht were left to rue those missed chances.
Connacht: Fitzgerald (Daly 66), Porch, Ralston, Hawkshaw, Hansen, Carty, Reilly (Blade 50); Dooley (Buckley 47), Heffernan (Stewart 60), Bealham (Aungier 60), Murray, Thornbury (Dowling 57), Murphy, Hurley-Langton (Oliver 57), Boyle (Booth 66).
Leinster: O'Brien, Turner, Ringrose, Ngatai (Henshaw 46), Russell (Frawley 72), R Byrne, Foley (N McCarthy 55); E Byrne (Porter 47), Sheehan (McKee 80), Furlong (Ala'alatoa ht), Molony, Ryan, Doris, van der Flier, Conan (Moloney 34).
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