Surrey face a battle to save their perfect start to their LV= Insurance County Championship title defence after seeing Kent build a substantial lead on day two at Canterbury.
The champions were all out for 145 in their first innings, with Matt Quinn taking 3-22 and Wes Agar 3-32, while India's Arshdeep Singh took his first Championship wickets.
Tawanda Muyeye then hit 79 and Daniel Bell-Drummond made 59 as Kent moved to 197-6 in their second innings, a lead of 353, but a productive evening session gave the visitors hope going into day three as Dan Worrall claimed 3-53.
Warwickshire, who occupy second place in Division One, have a firm grip at the halfway stage against Nottinghamshire at Trent Bridge and are poised to benefit if Surrey slip up.
By the time an approaching electrical storm had seen the players taken off just before 5pm, Nottinghamshire were in deep trouble at 82-5 in their first innings, still 489 runs behind after Warwickshire declared at 571-9.
Pakistan international Hasan Ali had taken two wickets in addition to his quickfire 54 with the bat, with wicketkeeper Michael Burgess grabbing two catches to go with his unbeaten 77 earlier.
Lancashire lead by 113 runs after two days of their match against Hampshire at Southport.
The visitors were indebted to a career-best six-wicket haul by Felix Organ after Phil Salt had struck his first century for Lancashire, with Daryl Mitchell and George Bell contributing significantly to the hosts' first-innings 374 to give the home side a huge 232-run lead.
A determined unbeaten second-wicket partnership between Fletcha Middleton (44 not out) and Nick Gubbins (45 not out) then helped take 95 runs off that advantage as Hampshire closed on 119-1 in their second innings.
Simon Harmer claimed his first five-wicket haul of the season as Essex put themselves into a strong position against Somerset.
Harmer had taken 18 wickets in his first six Championship appearances of the season but tore through the Somerset lower order after Jamie Porter had dealt with the top order and seen the visitors slump to 10-3.
Somerset were bowled out for 167 and trailed after the first innings by 295 runs, but Essex did not enforce the follow-on and ended the day on 15-1 - a lead of 310.
In Division Two, centuries from David Bedingham and Ollie Robinson provided the foundations as leaders Durham staged a fightback against Glamorgan.
The visitors reduced Durham to 119-4 to pile on the pressure, but Robinson and Bedingham responded with a stand of 171 for the fifth wicket and they finished the day on 411-5.
Worcestershire opener Jake Libby was left needing just two more runs to complete back-to-back double hundreds against Sussex after dominating on the second day at Hove.
It looked like being a day of unrelenting toil for Sussex when Libby and Adam Hose passed their first-innings score of 348 during a fourth-wicket stand of 192 either side of tea, but Sussex fought back admirably in the final hour to take six wickets.
Libby, though, proved immovable and will resume on Tuesday on 198 out of a total of 410-9, a lead of 62.
A brilliant exhibition of counter-attacking batting by Leus du Plooy and Haider Ali halted Yorkshire's victory charge in its tracks and rescued Derbyshire at Chesterfield.
Derbyshire's decision to move Ali down the order proved to be inspired as the Pakistani opener scored his first century for the county and shared an unbroken record-breaking fifth-wicket stand with Du Plooy of 231 from 311 balls.
They had come together with Derbyshire heading for defeat at 17-4 after Dawid Malan's 106 guided Yorkshire to 353 and a lead of 242 with spinner Mark Watt taking a career-best 5-83.
But Du Plooy's 96 and Ali's 129 lifted the home side to 248-4 and a lead of six when bad light, followed by an electrical storm, ended play with 10 overs left in the day.
Yorkshire had looked set for an even bigger lead until the dismissal of Malan sparked a collapse that saw the last five wickets fall for 28 runs.
Ollie Price celebrated his 22nd birthday with a career-best first class score as Gloucestershire fought back strongly against Leicestershire in Bristol.
Struggling at 118-5 early in the morning session, the hosts battled hard to post a first-innings total of 368, Price contributing 85 off 172 balls, with 12 fours.
