Derbyshire go down with a whimper
Derbyshire's slim hopes of avoiding relegation were over by lunchtime on Thursday and Warwickshire piled on the misery by completing a crushing innings-and-168-runs victory at the County Ground.
Keith Barker took five for 55 to help rout Derbyshire for 103 in their first innings, from which the absence of any batting points sealed their fate.
A return to Division Two of the LV= County Championship, just over a year after they were promoted as champions, was confirmed on the stroke of noon when Tony Palladino was forced to retire hurt at the end of the first innings.
With the Derby crowd resigned to disappointment, they then saw the home team skittled for 120 in their second innings to be beaten by the huge margin.
Nottinghamshire and Somerset, who were facing each other at Trent Bridge, could have been at risk if events had run quite differently in Derby.
As it proved, their fears were swiftly allayed, easing the pressure on their match.
Replying to Nottinghamshire's 406, Somerset were all out for 372, with James Hildreth making 161, and in their second bat the home side reached 139 for three with Steven Mullaney making a rapid 59 at the top of the order.
Keaton Jennings and Michael Richardson made centuries for champions Durham who were roused from an early slumber on day three against Sussex at Hove.
Durham trailed by 164 on first innings, and they shuffled uncomfortably to 111 for five at lunch second time around, but after the sandwich break Jennings and Richardson plundered 218 for the seventh wicket, with the latter removed by James Anyon for 129 to halt their partnership.
Opener Jennings, anchoring the innings, remained unbeaten on 113 at stumps, with Durham on 380 for seven and leading by 216 runs
In Division One's other game, relegated Surrey roared beyond Yorkshire's first-innings total at The Oval thanks to a double century from Dominic Sibley and a scorching ton from Hashim Amla.
Yorkshire's score of 434 put the pressure on, but Surrey had amassed 572 for four by the end of day three thanks largely to an undefeated steady-paced 220 from Sibley and Amla's princely 151 from 154 balls.
Northamptonshire could not mark their ascent to Division One with victory at Worcester, as it turned sour for them after lunch.
Set 257 for victory, after Worcestershire were bowled out for 295, Northamptonshire crumbled to 141 all out as Moeen Ali took six for 77 with his off-spin.
Elsewhere in Division Two, Hampshire defeated Essex by an innings and 31 runs at the Rose Bowl, where the away team subsided to 218 in their second innings. A brisk 53 from Graham Napier came too late for Essex.
Lancashire will head into the final day of the season in a commanding position against Kent at Canterbury, who reached the close on 32 for one as they chased 418 for victory.
Paul Horton made 106 and Ashwell Prince cracked 108 as Lancashire posted 393 for five in their second innings before inviting Kent to face the final overs of the day.
The dismissal of Daniel Bell-Drummond for eight by Oliver Newby proved the last act of the day.
Rain prevented any play on day three in Cardiff, with Glamorgan stuck on 271 for nine in their first innings, four shy of Gloucestershire's total.