Kent's Division One status was left dangling by a thread after a dismal day against Hampshire at Canterbury.
The hosts slumped to 64-5 in reply to Hampshire's first-innings 403 with Kyle Abbott claiming 3-23.
Hampshire took charge during the morning session as Tom Prest hit 102 and Brad Wheal added a career-best 61.
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Ryan Patel spearheaded a solid Surrey effort as the Vitality County Championship leaders defied closest challengers Somerset on a rain-hit second day at Taunton.
Patel was unbeaten on 61 having shared in a partnership of 80 with Ben Geddes (50) as the visitors reached 169 for three in reply to Somerset's 317.
The weather brought play to a close at 3pm though, with two games remaining, a draw would put Surrey in a commanding position in the table.
Warwickshire captain Alex Davies became the first player in Division One to score 1,000 Championship runs this summer on a shortened day against Worcestershire at New Road.
Davies scored 58 as his side reached 112 for four in reply to the hosts' 307 all out.
Worcestershire's final two wickets had earlier added just 13 to their overnight total.
Durham's David Bedingham also reached the four-figure mark as his unbeaten 177, combined with 111 not out from Colin Ackerman, put his side in control against relegation-threatened Lancashire at the Riverside.
The pair put on an unbroken 268 as the home side reached 367 for four having earlier restricted Lancashire to 228.
Michael Pepper scored a career-best 115 as Essex built a strong position against relegation battlers Nottinghamshire at Chelmsford.
Eclipsing his previous best - set just a week ago against Worcestershire - the wicketkeeper built on Tom Westley's earlier 122 to take Essex to a formidable 457 in their first innings.
Simon Harmer also weighed in with 51 before Nottinghamshire closed on 37 for one in reply after the loss of captain Haseeb Hameed.
Captain John Simpson became the first Sussex batter for 10 years to score five Championship centuries in a season as the Division Two leaders took charge against Glamorgan at Hove.
Simpson also passed 1,000 runs for the season in his unbeaten 112 as Sussex responded to Glamorgan's under-par 186 with 407-5.
Simpson shared in an unbroken stand of 194 for the fifth wicket with Tom Clark (79) after Daniel Hughes (83) had missed out on recording back-to-back centuries.
Promotion rivals Middlesex were frustrated by Gloucestershire's Ollie Price and the weather at Lord's.
Price was unbeaten on a gritty 56 as the visitors battled to 154-5, 223 behind, in the 41.4 overs possible.
Price's defiance came after his side had slipped to 74-4 with Toby Roland-Jones taking 3-12 in 16 balls, although his side still need a further 74 to avoid following on.
Yorkshire, also in the promotion picture, are on course for victory at Leicestershire despite rain limiting play to just a few hours.
Captain Jonny Tattersall, 90 not out overnight, hit 126 and Matthew Fisher added a career-best 88 as Yorkshire posted 379 for a first-innings lead of 281.
Fisher then struck twice as Leicestershire were reduced to 35-2 before rain forced the players off shortly before 2pm.
India leg-spinner Yuzvendra Chahal took five for 45 as Northamptonshire claimed the ascendancy against Derbyshire at Wantage Road.
Luis Reece (50) and Wayne Madsen (47) offered some resistance but Derbyshire lost their last six wickets for just 15 as they were bowled out for 165 and conceded a first-innings deficit of 54.
The hosts were 178-5 - leading by 222 - with Rob Keogh 46 not out at the close.
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