A last-minute try for Worcester handed them a much needed 17-14 Guinness Premiership victory over Gloucester at the Sixways Stadium on Saturday.
Trailing by two points for the entire second half Worcester left it until the last minute to break Gloucester hearts, Thinus Delport doing the damage.
Despite the defeat Gloucester go back to the top of the table, thanks to their losing bonus point.
The result gave Worcester a first victory over their neighbours at the 10th attempt, and consigned Gloucester to a sixth successive away loss in all competitions.
England wing Lesley Vainikolo's first-half try looked to have stirred Gloucester into action, after they trailed 12-0 to early Worcester touchdowns by centre Sam Tuitupou and wing Miles Benjamin.
Scrum-half Rory Lawson then pounced to inch Gloucester ahead by the break, and Worcester were left frustrated until Delport struck by grasping Benjamin's overhead pass with the final move of the game.
The Warriors, who saw wing Marcel Garvey carried off and taken to hospital after he bravely tried to halt juggernaut Vainikolo's touchline rampage, struggled to regain the upper hand following that injury setback.
But Worcester are 14 points clear of bottom club Leeds, entering the final four games in their Premiership campaign.
Gloucester moved back above Bath and Leicester, courtesy of a losing bonus point, yet they will need a considerable improvement when Heineken Cup quarter-final opponents Munster arrive at Kingsholm next Saturday.
Gloucester are still nowhere near recapturing the power and verve they displayed in abundance during the opening half of this season, and 2006 European champions Munster will fancy their chances.
Worcester included New Zealander Rico Gear on the bench following his recovery from injury and illness, while three Warriors faced their former club - Garvey, Delport and prop Tony Windo.
Gloucester were boosted by full-back Olly Morgan's first appearance since he suffered a dislocated shoulder in December, and lock Alex Brown also returned following surgery on a fractured jaw.
But there were only four survivors from Gloucester's last outing against Sale Sharks - centre Anthony Allen, prop Nick Wood, hooker Andy Titterrell and flanker Akapusi Qera.
Gloucester lost that game 22-16 - and this time they fell behind after just 62 seconds when Worcester scored a simple try following excellent approach work by the forwards.
The visitors' defensive organisation let them down badly as Tuitupou blasted through a gaping midfield hole to touch down unopposed.
Shane Drahm slotted the simple conversion, and Gloucester's early problems were underlined when Ryan Lamb knocked on in open play - much to his frustration as he disgustedly threw the ball away.
Gloucester could not get to grips with the wet and windy conditions and fell further behind midway through a half dominated by the home pack.
Garvey made inroads, cutting inside the Gloucester defence on an angled run, before fellow wing Benjamin powered over to score.
Even when Gloucester established a threatening territorial position they could not make it count as both Qera and Iain Balshaw were denied by last-ditch tackles.
But they finally struck eight minutes before half-time when Vainikolo was freed in space, and his trademark power saw him smash through two challenges.
Lamb converted. But there were concerns for Garvey, who was left prone on the turf.
He required extensive medical attention on the pitch before being carried off with an oxygen mask over his mouth for further assessment on what appeared to be a serious injury.
Gloucester settled far more quickly than their opponents in the aftermath, hitting them with a sucker-punch try deep into injury time.
Worcester seemingly switched off with the interval just seconds away, and they allowed Lawson to snipe over for a try that Lamb converted - edging the visitors 14-12 ahead.
Conditions deteriorated in the second period. But the elements did not deter a live wire Lawson from driving his forwards into the right areas during an increasingly attritional contest.As the rain lashed down, so Gloucester enjoyed a degree of control - ending a scoreless third quarter camped inside the Worcester half.
It looked as though they had the tactical acumen to ensure Worcester remained sufficiently far enough on the back foot - until Delport struck to spark wild celebrations.
Tries: Tuitupou, Benjamin, Delport
Tries: Vainikolo, Lawson
Cons: Lamb 2
Worcester: 15 Thinus Delport, 14 Marcel Garvey, 13 Dale Rasmussen, 12 Sam Tuitupou, 11 Miles Benjamin, 10 Shane Drahm, 9 Matt Powell, 8 Kai Horstmann, 7 Pat Sanderson (c), 6 Tom Wood, 5 Craig Gillies, 4 Greg Rawlinson, 3 Tevita Taumoepeau, 2 Aleki Lutui, 1 Tony Windo.
Replacements: 16 Darren Morris, 17 Matt Mullan, 18 Will Bowley, 19 Drew Hickey, 20 Joe Carlisle, 21 Jonny Arr, 22 Rico Gear.
Gloucester: 15 Olly Morgan, 14 Iain Balshaw, 13 James Simpson-Daniel, 12 Anthony Allen, 11 Lesley Vainikolo, 10 Ryan Lamb, 9 Rory Lawson, 8 Luke Narraway, 7 Akapusi Qera, 6 Alasdair Strokosch, 5 Alex Brown, 4 Marco Bortolami (c), 3 Carlos Nieto, 2 Andy Titterrell, 1 Nick Wood.
Replacements: 16 Jeremy Paul, 17 Alasdair Dickinson, 18 Will James, 19 Gareth Delve, 20 Gareth Cooper, 21 Willie Walker, 22 Chris Paterson.
Referee: Sean Davey
Touch judges: Paul Dix, Martin Buck
Assessor: Nigel Yates
Television match official: Matt Peters