Group 1: Durham v Essex; Warks v Notts; Worcs v Derbys
Group 2: Leics v Middlesex; Surrey v Glos
Group 3: Lancs v Yorks; Sussex v Northants
And that's all from us for this evening. Thanks for joining us, we hope you've enjoyed both the cricket and the much improved weather today.
We'll be back with day two from about 10:50 BST on Friday. See you then.
Essex 182 v Durham 58-6
Durham had done so well to survive the final nine overs unscathed after that clatter of earlier wickets... but then the very final ball of the day brings sees another one fall!
Sam Cook removes David Bedingham to leave the hosts 58-6, still trailing by 124.
Essex 182 v Durham 54-5
Which means we've got just one game remaining, at Chester-le-Street.
We're just entering the final over there...
Yorkshire 159 v Lancashire 94-1
A day to remember at Old Trafford as Lancashire stole the honours and kept their returning 2,000 crowd happy on the first day of the Roses Match.
After having Yorkshire in real bother at 40-7 approaching lunch, the Tykes wriggled off the hook a little to total 159 - thanks to a maiden half-century for teenager Harry Duke.
But Lancashire then got back on top again when they batted as Alex Davies breezed to a quickfire 52.
He went late in the day, but Keaton Jennings has stuck around for 22 off 94 balls to see his side to the close on 94-1, accompanied by Luke Wells, on 11, now just 65 behind.
Sussex 175 v Northants 91-4
That's stumps at Hove, where Northants close on 91-4, still trailing Sussex by 84.
While Northamptonshire have probably edged the day, Sussex will know wickets early on day two will even it up very quickly.
Warwickshire 250-6 v Notts
Hard going for Warwickshire at Edgbaston after being put in to bat by Nottinghamshire.
Half-centuries for skipper Will Rhodes (91) and Sam Hain (61) but run scoring has never appeared too easy - and the second batting point came up only in the last over of the day.
Dane Paterson has turned the game Notts' way with wickets in three successive overs late on - Hain's LBW decision having been followed by another against Michael Burgess and a Tim Bresnan duck, a sharp slip catch for Haseeb Hameed.
Matt Lamb is still there on 43, accompanied by Danny Briggs
Surrey 285-5 v Gloucestershire
South Africa great Hashim Amla struck an unbeaten century as Surrey enjoyed the better of day one against Gloucestershire at The Kia Oval.
The 38-year-old former Proteas batsman, who ended the day 103 not out, brought up his 54th first-class ton with his 12th boundary of the opening day.
He shared 104 with Jamie Overton - who reached 50 with the final delivery before stumps - for the seventh wicket, after Surrey had slipped from 105-1 to 181-5.
David Payne and Ryan Higgins were the pick of the Gloucestershire bowlers, taking two wickets apiece.
Worcestershire 330-7 v Derbyshire
The first day back in front of some of their fans in the best part of two years did not start well for Worcestershire at New Road when Daryl Mitchell was out first ball.
But it ended pretty well in the Worcestershire sunshine.
The only other low note was losing Ben Cox in the day's final over to trigger a slightly early end to the day's proceedings.
Cox was caught behind off Ben Aitchison for 49 after a stand of 88 with Ed Barnard, to follow the 114 put on earlier by Jack Haynes (97) and Brett D'Oliveira (71).
Worcestershire's day and a likely four batting point to follow in the morning. But don't write off Derbyshire until they've batted on this strip too.
Surrey 283-5 v Gloucestershire
Hashim Amla's 12th boundary - a drive through the covers - brings up his 54th first-class century.
The South Africa great has played superbly today and his partnership with Jamie Overton, now worth more than 100 after that stroke, has been really important.
Overton himself is on 49.
Sussex 175 v Northants 81-4
Sussex have used four different bowlers in this evening session and all four of them have now taken a wicket.
Jack Carson dismisses Rob Keogh for 24.
Surrey 278-5 v Gloucestershire
Hashim Amla is onto 99 at The Oval with a flashing drive.
Three overs remaining for the day.
Middlesex 260-7 v Leicestershire
That's stumps at Leicester, where John Simpson's 73 not out has given Middlesex hope on the opening day.
Callum Parkinson was the most productive of the home bowlers, taking 3-76.
Essex 182 v Durham 40-5
So often Essex's bowlers get their batsmen out of a pickle and they're doing a decent job of that today too.
They've now got Durham 40-5, after Peter Siddle traps Jack Burnham lbw for two, still 142 runs in arrears.
Hain lbw Paterson 61 (Warwickshire 238-4 v Notts)
Sam Hain goes for 61 as Dane Paterson makes a late breakthrough.
After putting on 71 with Matt Lamb (39), Paterson traps him LBW.
Six overs to go in the day at Edgbaston and Warwickshire continue to build, but only slowly. They look on course for a second batting point b but will have to speed up to get any more.
Worcestershire 322-6 v Derbyshire
There's something extra special for Worcestershire supporters when Ben Cox and Ed Barnard get together.
They were the pair at the crease the night Worcestershire won their last trophy, the 2018 T20 Blast, having already performed heroics in the semi. And, whether they're wearing all white or one-day blue, they often bat well together.
They're at it again today as they build on the earlier good work by Jack Haynes and Brett D'Oliveira.
They have so far put on 74 for the seventh wicket - and earned the Pears two more batting points. Cox on 42, Barnard on 41
Four overs to go in the day at New Road.
Essex 182 v Durham 37-4
Sam Cook strikes again - another lbw, too - dismissing Michael Jones for four.
Nine wickets have now fallen for 40 runs across the two innings.
Surrey 268-5 v Gloucestershire
Hashim Amla is nine away from his 54th first-class century.
Partner Jamie Overton is on 46, with the pair now having put on 87 together.
Seven and a bit overs left in the day.
Essex 182 v Durham 37-3
Scott Borthwick and Cameron Bancroft fall in quick succession!
All three wickets have fallen lbw, Borthwick dismissed by Sam Cook and Bancroft by fellow Australia Peter Siddle for 20.
Essex still well in this.
Davies c Duke b Olivier 52 (Yorkshire 159 v Lancashire 71-0)
No sooner has he reached his 50 than Alex Davies is gone.
Umpire Steve O'Shaughnessy adjudges that he has feathered an edge down the leg side off Duanne Olivier in the 19th over - and Yorkshire at last have a breakthrough.
New man in is Luke Wells, Lancashire's experienced winter signing from Sussex.
Yorkshire 159 v Lancashire 71-0
Half century for Alex Davies at Old Trafford. 51 off 53 deliveries. Eight fours, Great knock.
Lancashire almost half way to Yorkshire's score, No wickets lost. A good day for the Roses Well the Red ones anyway!
No doubt it will help ease a little of the pain suffered up the road at the other Old Trafford last night.