Essex 86 for 3 Trail Derbyshire 146 (Du Ploy 43, Snater 3-45) by 60 runs
Essex kept alive their bleak hopes of qualifying for Division One by taking advantage of Derbyshire's delicate batting on day one of the LV=Insurance County Championship match in Derby.
Shane Snater took 3 for 45 as Derbyshire were skittled for 146, only to offer any longer resistance with a 91-ball 43 after batting with only Luis du Ploy.
Jamie Porter, Simon Cooke and Jimmy Neesham took two wickets each to bowl Derbyshire out for less than 150 for the eighth time in 12 innings.
Derbyshire returned with Fain Hudson-Prentice returning to Sussex at the end of the season, taking two wickets, leaving Essex 3, 60 for 86.
Derbyshire's decision to bat with the floodlights on on a flooded morning soon looked questionable as they were bowled out for 31 for 3.
Tom Wood lost his off-stump to Cook without a shot, was lbw to Lewis Reece, who was caught behind by the snatter, and was thrown between bat and pad by Porter to Brooke Guest.
Matt Critchley played across the line at Cook and though du Ploy converted Snatter into T20 mode for six runs, it was a rare bright spot for the home side.
Harry Kemm went early on his first-class Derbyshire debut, was caught to pursue Simon Harmer in the second over after lunch and the slide continued with Harvey Hossen driving on a porter.
Du Ploy came on the pitch to seamer to reduce the risk of falling lbw, but he was legged before the snatter and Neesham polished the tail, after missing a drive from Alex Thomson.
Having scored maximum bowling points, Essex now needed to do the same with the bat and it looked ominous for Derbyshire when Alastair Cook was dropped by Critchley at second slip for 7.
Cook advanced on 30 but Rees found enough movement to breach his defense and struggled before captain Tom Westley overtook Hudson-Prentice.
Hudson-Prentice caught Michael Pepper at cover and although Nick Brown and Neesham prevented further failures, Essex would have to put in a bigger effort to get home full of bonus points.