Bath finally surrendered their unbeaten home league record against Gloucester despite a brave late fight back at the Rec.
After trailing 21-5 with little more than 10 minutes to play, two late tries ensured Bath at least took a bonus point from what was a frustrating afternoon for Steve Meehan's team.
Gloucester went into the match without a win on Bath soil since leagues began in 1987 - but an error-strewn performance from the hosts allowed their fierce rivals to put that record to bed.
Gloucester, beaten by Leicester on the opening weekend, were slicker and more cohesive than their opponents and deservedly claimed that first win at the Rec.
Bath clicked into gear in the closing minutes, with late tries from Joe Maddock and Nick Abendanon giving them hope - but Gloucester held firm to seal the four points.
"The fightback is supposed to start in the first minute of the match," said head coach Meehan. "But we lost our way and the speed of our game wasn't what it should have been. We saw in the last 15 minutes that when the tempo is up there and we use the width we are threatening. It was disappointing and there will be some truths told on Monday."
Gloucester made a flying start when Willie Walker dropped a goal from the 22-metre line inside the opening minute, before missing a long-range penalty.
Bath punished his miss when they kicked a penalty to touch, Peter Short secured possession at the back of the line-out and put Jonny Fa'amatuainu through a gap. He was stopped, but managed to pop the ball up to returning skipper Michael Lipman to score.
Fly-half Butch James missed the conversion - as he did two first-half penalties - as Bath failed to capitalise on a brief period of dominance.
And Gloucester took advantage when Walker slotted a penalty after Bath were penalised at the ruck - and despite losing lock Will James to the sin bin on 32 minutes, Gloucester increased their lead through another Walker penalty.
James Simpson-Daniel's tackle on Matt Banahan denied Bath a try early in the second half, before two more penalty misses by Springbok star James took his missed points tally to 13 for the afternoon.
Gloucester soon made Bath pay, No 8 Luke Narraway picked up from the base of a scrum 30 metres out and ran through unopposed to score. Walker missed the conversion but the visitors now led 14-5.
And that became 21-5 when James was charged down by Walker just inside the 22 - and the Kiwi ran through to score next to the posts and convert his own try.
Bath looked a beaten team at that point - but then played some of their most fluent rugby of the match in the closing stages.
First they worked the ball wide from a line-out, with Maddock being put through a gap to score out wide. Shaun Berne's conversion made it 21-12.
And then they added a third try when Abendanon stepped past Mike Tindall and into space - and raced in to reduce the deficit even further, although Berne missed the conversion.
Bath sensed victory - but they had left it too late, and Short's knock-on in a wide position signalled the end of the contest and Gloucester's first ever league win at the Rec.