GLOUCESTERSHIRE blew the LV=County Championship Second Division promotion race wide open by becoming the first team to beat leaders Derbyshire this season.
Having dominated the first two days, Gloucestershire confirmed their superiority when carving out a comfortable seven-wicket inside-the-distance win at Bristol.
Derbyshire were bowled out for 283 in their second innings, their last seven wickets realising just 95.
Seamers David Payne and Will Gidman, who took eight wickets in the match, did the damage, returning figures of 4-89 and 4-50 respectively.
Gloucestershire then chased down a modest victory target of 85 for the loss of Jon Batty, Benny Howell and Kane Williamson.
This was Derbyshire's first defeat in eight Championship outings this summer and their demise will give hope to the chasing pack.
Gloucestershire director of cricket John Bracewell maintained the first hour was going to prove decisive and so it proved.
Resuming on 211-5, just 12 runs ahead, Derbyshire needed to bat beyond lunch in order to make a game of it. But they lost a wicket to the 12th ball of the day, David Wainwright edging Payne to first slip where Alex Gidman displayed safe hands.
Much depended upon Dan Redfern, 64 not out overnight, and the former England Under-19 international appeared set to pass three figures as he advanced to 77 in confident fashion before rain intervened.
A 30-minute break did the left-hander no favours and, his concentration broken, he fell tamely to the first ball after the resumption.
Wafting at a shorter delivery from Payne outside off stump, Redfern succeeded only in offering a straightforward catch to Kane Williamson at cover.
Ian Saxelby weighed in with the wicket of Tom Poynton soon afterwards, Derbyshire's wicketkeeper being pinned on the front foot, as the visitors subsided further and it was left to Payne to apply the coup de gras shortly before lunch.
Gloucestershire's left arm seamer pinned Tony Palladino in the crease and then repeated the feat with his very next delivery to remove Tim Groenewald, leaving Jon Clare high and dry on 43 not out.
Their team requiring a modest 85 to win, Gloucestershire supporters were reminded of a game between these two sides in Bristol in 2010. Chasing a target of 125 on that occasion, Gloucestershire were bowled out for 70 to hand Derbyshire victory after they had been dismissed for 44 on the first morning.
But Gloucestershire's batting is made of sterner stuff these days and the top-order ensured there was to be no repeat of that particular calamity, Howell and Williamson calming any nerves in a stand of 52 for the second wicket, after which Alex Gidman and Hamish Marshall saw them safely home.
Gloucestershire's second win in eight games this season netted them 21 points, while Derbyshire took just three.