Runaway leaders Derbyshire were put firmly in their place by lowly Gloucestershire on the opening day of the Division Two match at Bristol.
Yet to lose a four-day game this season and well clear of their nearest rivals going into this game, the surprise early-season front-runners were all out for just 95 inside 33 overs - their lowest score of the summer - after winning the toss, with Will Gidman taking four for 29 in eight overs.
Gloucestershire then made good their advantage on a true pitch, overseas batsman Kane Williamson and skipper Alex Gidman posting half centuries to help the home side reach the close on 182 for five, already 87 runs ahead.
Derbyshire's hitherto in-form batsmen succumbed to a combination of poor shot selection, suicidal running between the wickets and disciplined bowling from a Gloucestershire seam attack that adhered admirably to the tenets of line and length.
Gloucestershire's decision to recall David Payne following injury paid immediate dividends, the left-armer undermining Derbyshire's top-order during an incisive spell of three for 21.
The former England Under-19 international extracted additional bounce to remove in-form opener Martin Guptill - who deflected a short delivery onto his stumps - and then Wayne Madsen edged to second slip.
In-between those dismissals, left-hander Matt Lineker offered a regulation catch behind, forced into front foot indiscretion by a full-length delivery.
Instead of learning their lesson, Derbyshire's batsmen continued to adopt an aggressive approach against the swinging ball and succumbed to a blistering spell from Will Gidman shortly before lunch.
Gloucestershire's talented all-rounder surge included a spell of three wickets in seven balls.
Dan Redfern mis-timed a pull shot and was brilliantly held at deep square-leg by Ian Saxelby and Wes Durston was caught by Chris Dent at second slip in the act of cutting.
David Wainwright lost his off stump to a ball that left him and Tom Poynton offered a catch at the wicket as the visitors slumped from 63 for two to 83 for eight at lunch, with Saxelby weighing in with the wicket of Jon Clare.
Their previous lowest championship score this season - 130 against Glamorgan at Cardiff in April - was already looking beyond the visitors.
Derbyshire added to their own discomfiture in the afternoon session, Tony Palladino needlessly running out Ross Whitely and then succumbing in similarly hapless fashion himself.
Although Gloucestershire openers Jon Batty - promoted up the order owing to an injury suffered in the field by Chris Dent - and Benny Howell departed cheaply, Alex Gidman and Williamson confirmed the home side's superiority in a third-wicket stand of 81 in 30.5 overs.
Williamson had raised an eye-catching 56 from 112 balls, including 10 fours, when Tim Groenewald found his outside edge and the New Zealander was brilliantly caught behind by a full-length Poynton.
Hamish Marshall was bowled by Whiteley in the act of driving for 31 and nightwatchman Liam Norwell fell to the same bowler in the penultimate over as Derbyshire staged a late fightback.
But the resolute Gidman, who raised 50 from 125 balls, was still there at stumps on 72 not out.
