Derbyshire are staring down the barrel of relegation to Division Two after suffering a top-order collapse on day two of their home clash against Warwickshire.
The visitors declared on 391-9 in their first innings at Derby before their opponents, who need a win to stay up, were reduced to 44-5 when bad light ended play.
Chris Woaked (152 not out) and Maurice Chambers (58) built a Warwickshire-record ninth-wicket stand of 166 before the latter combined with Keith Barker to tear through Derbyshire.
Rain had washed out the morning session but when the game resumed under the floodlights, Woakes and Chambers continued their history-making partnership to deny Derbyshire a third bowling point.
Chambers, who is on loan from Essex, passed his previous highest score of 30 and the record ninth-wicket stand at Derby of 135 between Harry Parks and Tich Cornford for Sussex in 1935 fell soon afterwards.
Woakes went on to beat his previous career-best score of 136 and was still at the crease with Chambers when the next milestone of Warwickshire's previous highest ninth-wicket stand of 154 was surpassed.
The partnership finally ended when Chambers was stumped when charging at David Wainwright, leaving Woakes to complete his 150 before captain Varun Chopra waved the innings off.
Chambers was soon among the wickets and with Barker (3-21) also moving the ball late, Derbyshire were quickly in big trouble.
Ben Slater (2) was trapped lbw off the third ball of the innings, skipper Wayne Madsen (1) edged Chambers to first slip and Paul Borrington (0) was snared at gully to leave the home side reeling on 9-3.
Chambers then had Richard Johnson (4) caught by Rikki Clarke at second slip with only 14 on the board, and when Alex Hughes (4) was caught behind off Barker, Derbyshire were crumbling at 33-5.
Shivnarine Chanderpaul (24 not out) played a couple of defiant drives before bad light and then drizzle brought a halt at 5.15pm with Derbyshire still in dire straits.