Browne and Lawrence underline Essex's batting talent
Derbyshire 124 for 2 trail Essex 538 for 7 dec (Browne 255, Lawrence 116, Ryder 51, Thakor 4-107) by 414 runs
Derbyshire face two tricky days at the crease if they are to prevent Essex extending their lead at the top of the Specsavers County Championship Division Two after Nick Browne took his innings to a mammoth 255.
The visitors negotiated 41 overs in their first innings, but still need another 264 runs to make Essex bat again.
It was not the position Derbyshire expected to be in when they took up the option of an uncontested toss on day one, only for Essex to take full advantage of the conditions and rattle up 538 for 7 before declaring.
Essex's highest total of the season so far was anchored by Browne, who eclipsed his previous highest first-class score by more than 100.
Essex had declared when they lost three wickets in 16 balls to Shiv Taylor as they chased quick runs in the early afternoon.
Browne and Jesse Ryder smashed 90 runs in a 10-over post-lunch blitz - which was in contrast to the first four sessions when they trundled along at little more than three an over.
Dan Lawrence added 65 to his overnight 51, reaching his century from 181 balls with 10 fours, before he got an inside edge in Chesney Hughes's first over.
He had put on 210 for the fourth wicket with Browne in 64 overs, though the pair decided against a quick run chase in the morning in pursuit of a fourth batting point. Essex were 12 runs short of that milestone in the end.
But there was no such reticence after the break as Browne threw off his earlier circumspection to join Ryder as Essex added 128 in less than 15 overs before calling a half to the carnage.
Browne even lofted Shiv Thakor over long-on for a six as well as reverse-sweeping Hughes for one of 34 boundaries in his career-best 255. His nine-hour stay at the crease ended five balls after Ryder had gone for 51.
Ryder charged down the wicket to Thakor's first ball of the over and was stumped by Tom Poynton. Browne then got a leading edge and was caught at mid-off by Hamish Rutherford. He faced 445 balls during his marathon.
Thakor took his third wicket in 16 balls, for career-best figures of four for 107, when he trapped James Foster lbw for 17.
Derbyshire had begun the day with a worrying minus five against them in the over-rate column. But with wicketkeeper Poynton leading the between-over sprints, and Matt Critchley, Wayne Madsen and Hughes all coming in off a couple of paces, they bowled 38 overs in the morning session. By lunch the deficit was minus one; when Essex declared an hour later they were two in credit.
Aaron Beard, the 18-year-old Chelmsford-born pace bowler making his Championship debut, claimed his first scalp when he removed Billy Godleman's offside in his first over after tea.
Beard had worried the Derbyshire bowlers from the start with Hughes and Godleman having to dig out several of yorker length. Those that strayed fractionally, however, were despatched to the boundary, two in succession by Godleman into the exposed off side.
Hughes's 88-ball innings ended for 37 when Ravi Bopara's third ball ripped out his off-stump as he attempted to drive past the bowler.
Bopara thought he had Wayne Madsen caught behind before the close when he was on 2, a verdict backed vociferously by the slip cordon, though the way it looped through suggested it probably flicked pad rather than bat.