Former England all-rounder Tim Bresnan scored a debut century to put his new county Warwickshire in control against Northamptonshire in the Bob Willis Trophy.
Bresnan, who left Yorkshire after 19 years in June, struck 105 on day two at Edgbaston as Warwickshire posted 369 for eight from their 120 overs in reply to the visitors' 142.
Openers Ben Curran and Emiliano Gay survived seven overs as Northamptonshire closed on 19 without loss in their second innings, trailing by 208.
Nick Gubbins fell eight short of a double century as Middlesex declared on 347 for six against Surrey at the Kia Oval.
Gubbins, 150 not out overnight, hit 19 fours and a six in his 315-ball knock, which was supplemented by 53 from John Simpson.
Surrey closed on 189 for three in reply with Scott Borthwick 73 not out.
Somerset were in complete control against Glamorgan at Taunton.
Craig Overton finished with five for 38 as the Welsh side were shot out for just 131 in response to the hosts' 296.
Somerset then extended their lead to 296, with James Hildreth 45no and captain Tom Abell 44no as they reached 131 for two at stumps.
Former England captain Sir Alastair Cook managed just eight as county champions Essex reached 179 for five in response to Kent's 387 at Chelmsford.
Nick Browne made 61 and Varun Chopra 41 but visitors will be hoping Ryan ten Doeschate (22no) and Adam Wheater (24no) can add to their unbroken 35-run stand.
Earlier, Heino Kuhn failed to add to his overnight 140 in Kent's innings, becoming one of four victims for Jamie Porter. Marcus O'Riordan was left on 42no.
Sussex were hoping to set Hampshire a challenging target at Hove after claiming a first-innings lead of 23.
They led by 178 at the close after bowling Hampshire out for 153 and reaching the close on 155 for six.
England hopeful Phil Salt got their second innings off to a fine start with 80 after Ollie Robinson and Mitchell Claydon had finished with three wickets apiece to wrap up the Hampshire first innings.
Worcestershire appeared to have the upper hand against Gloucestershire at Bristol, ending the day just 44 runs behind with eight first-innings wickets in hand on 223 for two.
Daryl Mitchell had led the response with 80. Earlier Charlie Morris finished with four for 52 as Gloucestershire were bowled out for 267.
Durham battled back in their low-scoring contest with Yorkshire at Chester-le-Street, ending the day with a lead of 10 on 106 for two in their second innings. Alex Lees was unbeaten on 58.
Chris Rushworth, Ben Raine and Paul Coughlin finished with three wickets apiece as Durham, who were skittled for 103 first time around, bowled out Yorkshire for 199.
In a game being played at Worcester, Ben Slater hit an unbeaten 104 as Leicestershire reached 183 for two in reply to Lancashire's 322. Slater put on 153 for the opening wicket with Hassan Azad (58).
Nottinghamshire were in a strong position against Derbyshire at Trent Bridge despite a century from the visitors' Leus Du Plooy.
Du Plooy hit 130, adding 80 in a crucial last-wicket stand with Samuel Connors, but Derbyshire still conceded a deficit of 85 as they were bowled out for 239. Notts were 84 for three at the close.
