David Masters claimed another five-wicket haul before Derbyshire's lower order fought back strongly to leave the LV= County Championship Division Two match against Essex at Derby fascinatingly poised.
The pace bowler finished with impressive figures of five for 51 from 30 overs but half-centuries from Ross Whiteley and Tom Poynton helped the Division Two leaders rally to reach 266.
Essex lost Jaik Mickleburgh in the fourth over of their second innings, but an attacking unbeaten half-century from Tom Westley carried the visitors to stumps on 85 for one, a lead of 64.
Yorkshire's promotion bid was again hit by rain as they suffered a washout for the second successive day against Gloucestershire at Scarborough.
Niall O'Brien struck a career-best 182 but Northamptonshire's clash against Glamorgan at Cardiff appears doomed to end in a tame draw.
Glamorgan had hoped to set up a winning position going into the final day but Northamptonshire seemed happy to settle for a share of the spoils.
Northamptonshire eventually declared their first inning 30 minutes before the end of the third day on 432 for eight. At the close Glamorgan had reached 10 for nought from seven overs.
Kent's bid for promotion looked in the balance with one day left of their crucial rain-hit game against Leicestershire at Grace Road.
After Kent declared at 350 for eight, the hosts reached stumps on 171 for three, only 30 runs short of avoiding the follow-on.
Fourth-placed Kent need a victory to keep their promotion hopes alive.