Bath inflicted a second defeat of the season on Guinness Premiership leaders Gloucester on Friday at the Rec, winning a battle of attrition 10-5 in a quagmire.
Joe Maddock's try, the end product of a moment of inspiration by Nick Abendanon, proved the difference between the two teams, although even the most one-eyed Gloucester fan would admit that Bath were deserved vidtors of the West Country derby.
Gloucester remain two points clear of their fierce west country rivals, but they have still to win a league game on Bath soil in 17 attempts.
England centre Olly Barkley's goalkicking and wing Maddock's 50th-minute try decided a contest totally dictated by appalling weather.
The game only narrowly survived the elements, yet Bath were full value for a victory that means they have already equalled their total number of league wins - eight - registered last season.
Gloucester were hustled out of their stride by a vastly-superior Bath pack, a huge collective effort highlighted by superb individual displays from flanker Michael Lipman and number eight Daniel Browne.
Gloucester substitute Chris Paterson's breakaway try 19 minutes from time caused a few flutters in the Bath ranks, yet the home side were not to be denied a win built on fearless commitment.
Gloucester arrived without first-choice wings Lesley Vainikolo and James Simpson-Daniel.
Former Bradford Bulls rugby league star Vainikolo - the Premiership's top try-scorer this season - has flown home to New Zealand to deal with what Gloucester have termed "a serious family problem".
England international Simpson-Daniel, meanwhile, missed out because of flu, so James Bailey and Leon Lloyd were drafted into a Gloucester side seeking a ninth league win in 10 starts.
Bath, unbeaten in Premiership action on home soil since September 2006, made 11 changes after their 25-10 defeat against Wasps last time out.
Torrential rain meant surface water covered large areas of the pitch, and referee Wayne Barnes delayed the kick-off by 15 minutes after speaking to Bath skipper Steve Borthwick and his Gloucester counterpart Marco Bortolami.
Barnes' decision gave the Bath groundstaff more time to sweep and mop the water away, but conditions were far from ideal for a game of such importance, and it only went ahead after he conducted a second detailed inspection.
The Bath forwards made an aggressive start, looking to dictate play, and tempers quickly boiled over, with Barnes issuing a warning to home prop David Barnes and Gloucester hooker Olivier Azam.
Barkley's opening penalty shot fell short - he gained the opportunity after Borthwick was tipped dangerously from a lineout - and Bath continued pressing.
Gloucester took a while to settle, with Bath remaining on top throughout a scoreless opening quarter that was notable only for two powerful runs by Bath's 6ft 7in wing Matt Banahan.
Despite the sodden surface, Bath adopted an adventurous approach, keeping the ball alive and looking to attack through the midfield channels of Barkley and fly-half Butch James.
It kept the Gloucester defence busy, even if much of Bath's intricate work took place between both 10-metre lines.
A stamina-sapping contest began to take its toll as half-time approached, with Bath centre Alex Crockett and opposite number Mike Tindall requiring treatment after being on the receiving end of separate collisions.
But Bath went ahead when the impressive Barkley slotted a 33rd-minute penalty, handing the home side an interval advantage which they richly deserved following their domination of possession and territory.
And it took the home side just 10 minutes of the second period to convert that lead into a more commanding position.
Relentless pressure deep inside Gloucester's 22 looked to have floundered when the visitors hacked possession clear, but full-back Nick Abendanon's brilliant kick into space enabled Maddock to gather a kind bounce and dive over.
Barkley converted from the touchline, hoisting Bath 10 points clear and leaving Gloucester with a mountain to climb as head coach Dean Ryan made a triple substitution, sending on prop Patrice Collazo, hooker Jeremy Paul and flanker Alasdair Strokosch.
Paterson followed a minute later, and he made an immediate impact, scoring with his first touch by sprinting over from 50 metres before seeing his conversion attempt hit the post.
The try removed any hint of complacency in Bath's ranks, and Gloucester suddenly looked a different team with Paterson calling the shots from fly-half instead of Ryan Lamb.
Bath had to tighten things up again, but they had enough in the tank to keep Gloucester at a safe distance and inflict only a second defeat of the league campaign upon them.
Bath: 15 Nick Abendanon, 14 Joe Maddock, 13 Alex Crockett, 12 Olly Barkley, 11 Matt Banahan, 10 Butch James, 9 Michael Claassens, 8 Daniel Browne, 7 Michael Lipman, 6 Andy Beattie, 5 Danny Grewcock, 4 Steve Borthwick (c), 3 Matt Stevens, 2 Lee Mears, 1 David Barnes.
Replacements: 16 Pieter Dixon, 17 Paulica Ion, 18 Peter Short, 19 Jonny Faamatuainu, 20 Nick Walshe, 21 Shaun Berne, 22 Michael Stephenson.
Gloucester: 15 Willie Walker, 14 James Bailey, 13 Mike Tindall, 12 Anthony Allen, 11 Leon Lloyd, 10 Ryan Lamb, 9 Rory Lawson, 8 Luke Narraway, 7 Akapusi Qera, 6 Peter Buxton, 5 Alex Brown, 4 Marco Bortolami (c), 3 Carlos Nieto, 2 Olivier Azam, 1 Nick Wood.
Replacements: 16 Jeremy Paul, 17 Patrice Collazo, 18 Will James, 19 Alasdair Strokosch, 20 Mike Prendergast, 21 Chris Paterson, 22 AN Other.
Referee: Wayne Barnes
Touch judges: Paul Dix, Peter Huckle
Television match official: Laurie Bryant, Graham Hughes