Leinster coach Joe Schmidt may have been happy to emerge from a bruising battle in Bath with a win, but he was unhappy with the lack of precision in the reigning Heineken Cup champions' game.
There were at least two occasions in each half when Leinster should have scored, yet the only try of a tight game came from England centre Matt Banahan for Bath.
Even so, the accurate boot of man of the match in the 2011 Heineken Cup final, Jonny Sexton, was enough to steer the Irish province to a 18-13 triumph that put them three points clear of Glasgow Warriors at the top of Pool 3.
"The frustration was that we couldn't get the ball over their line. We appeared to have a couple of gilt-edged chances," admitted Schmidt in his post-match verdict on leinsterrugby.ie.
"Against a quality team it's hard to create opportunities, and the last thing you want to do is butcher them like we did. We almost suffocated ourselves at times.
"We want to be a lot more accurate to make sure we finish opportunities that we create, but I am delighted with the result."
More than 40,000 tickets have been sold for the return leg at the Aviva Stadium on Saturday night, when Bath will have to win to keep alive their slim hopes of qualifying for the last eight.
Finals Edition: Listen to the best guide to the European Rugby Cup Finals weekend in Dublin, which sees Leinster Rugby take on Stade Francais Paris at the RDS on Friday night in the Amlin Challenge Cup Final and then ASM Clermont Auvergne tackle Toulon in an all-French affair at the Aviva Stadium on Saturday.