Graham Napier's superb bowling and an unbeaten century from Jaik Mickleburgh enabled Essex to enjoy the better of the second day in their LV=County Championship match against Leicestershire at Chelmsford.
The hosts reached stumps on 216 for four in reply to an all-out total of 365 by Division Two's bottom side.
The morning session saw Napier, with his brisk pace, produce a sensational spell after the visitors had moved beyond 350 with only four wickets down.
Napier got rid of overnight pair Ned Eckersley and Matthew Boyce, who shared a century stand, and went on to rip through the tail, claiming five wickets in the space of 15 deliveries at a personal cost of just three runs.
The visitors lost their last six wickets for as many runs, having resumed on 328 for four and progressed to 359 without further loss before falling apart.
Napier embarked upon his destructive trail by having Boyce caught behind for 54 to end a stand of 147. He then ended the fine innings of Eckersley by deceiving him with a slower delivery, but not before the right-hander had moved to a career-best 147.
That effort contained 17 fours and two sixes and embraced 277 deliveries, but Napier soon provided a further lift for Essex, bowling Anthony Ireland and Alex Wyatt after Josh Cobb had been caught.
He finished with figures of 5-77 from 20.3 overs - a fine follow-up to figures of 7-90 when the counties met at Leicester in their previous championship meeting.
Napier's performance came on a day when fellow paceman David Masters missed the action after being caught in a traffic jam following a pile-up on the M25.
The former Leicestershire bowler did not arrive until after lunch, by which time the Essex reply was well under way.
Mickleburgh and Hamish Rutherford set a firm foundation with a stand of 61, before the New Zealander was guilty of a careless stroke against Ireland to be caught by Wyatt at deep backward square-leg.
Greg Smith quickly followed when he edged to Joe Burns in the slips and provided off-spinner James Sykes with a maiden championship wicket on debut.
Owais Shah also perished when he pushed forward against Wyatt to be caught behind just before the 100 was raised and Ryan ten Doeschate lazily drove Ollie Freckingham to mid-off.
Amid the setbacks, Mickleburgh grew in confidence and punctuated the field with several well-timed strokes en route to his first century of the summer.
He eventually got there by cover-driving Shiv Thakor to the boundary for his 13th four and added another three boundaries to close with 121.
Keeping him company was Ben Foakes, who will resume tomorrow on 25 and has so far helped the opener add 65 for the fifth wicket.