Somerset bowl out Warwickshire for 121 at Edgbaston
England's Dawid Malan makes hundred for Yorkshire
Slater and Duckett hit centuries for Notts against Lancashire
All 18 counties split into three regional groups of six
Each side will play five games
Two teams with most points contest five-day final
Yorkshire 178-4 v Derbyshire
We'll have to wait for the final session to begin at Headingley, where rain arrived while the players were taking tea. Remember when it was 30 odd degrees last weekend......
Glamorgan v Gloucestershire - play abandoned
The umpires decide enough is enough at Sophia Gardens and the teams will return on Sunday in the hope of better weather and the chance of making up for lost time.
Glamorgan have one draw and one defeat so far in Central group, while the visitors have one win and one draw.
Yorkshire 178-4 v Derbyshire - tea
Image source, Rex FeaturesNeither team has a clear advantage after two sessions of the clash between North group's top two at Headingley.
Derbyshire will have been happy to get rid of Jonny Bairstow for only 22, but it is another England player, Dawid Malan, who is playing the kleading role as Yorkshire look for a sizeable first-innings total.
He has 75 not out at tea, having added 72 with Johnny Tattersall so far.
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Earlier, we asked you to tell us which current player you'd most like your favourite county to sign and why. Still plenty of time to air your opinions, so please send 'em our way.
Nottinghamshire 210-1 v Lancashire - tea
Lancashire must be sick of the sigh of Ben Slater.
After scoring 172 against them during a two-week loan spell with Leicestershire, he is in the runs again and only eight short of a centrury as the teams take tea at Trent Bridge.
He has hit 13 fours so far, but could be beaten to three figures by partner Ben Duckett, who has contributed 91 not out to their stand of 140.
They have had their streaky moments, though.
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Yorkshire 161-4 v Derbyshire
Having had to surrender the wicketkeeping gloves to Jonny Bairstow for the time being, Johnny Tattersall is intent on proving his worth to the club as a specialist batsman in the middle order.
And he's doing a solid job so far in support of Dawid Malan as they rebuild the innings after the loss of Adam Lyth and Harry Brook in the same over.
Malan is 67 not out and Tattersall has 27 - although his second boundary was fortunate, an under-edge all along the ground past the diving keeper.
Hampshire v Surrey 79-5
Bad light has forced an early tea at Arundel where Surrey, somewhat surreally, will be quite happy to be 79-5.
When you lose your first five wickets for 36 runs, an unbroken 43 partnership is like manna from heaven really.
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Simon Hancock: Just as well England have taken away Somerset's top two spinners just so other batting teams have a chance.
Good point, Simon - Somerset's bowling figures have been sensational even without Dom Bess and Jack Leach.
Somerset, by the way, have begun their reply to Warwickshire's 121 all out, carefully ambling to 16-0 after six overs.
Haines c Harmer b Porter b 14 (Sussex 38-1 v Essex)
You can't keep that man Harmer out of the game for long.
Tom Haines tries to drive a ball from Jamie Porter, edges and second slip Harmer turns to his right to safely take the catch at chest height.
Not only is he a superb spin bowler, but he's also a very safe pair of hands.
Image source, Rex FeaturesNottinghamshire 204-1 v Lancashire
The first point is on the board for Notts as George Balderson overpitches and Ben Duckett spanks it past mid-off four four. He has 79, Ben Slater is on 90 and everything is set fair for the 'visitors' at Trent Bridge, except maybe the weather. But let's hope rain will stay away.
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Kent v Middlesex 22-1
Image source, Rex FeaturesAs feared, the ongoing deluge of rain at Canterbury has forced the umpires to call a premature halt to proceedings.
A huge blow to both sides, who really need an outright result in this game if either are to catch South Group leaders Essex.
Great weather for ducks - and other creatures of the winged variety, as you can see bottom left of the picture where a pond is forming on the Canterbury pitch - but not great weather for cricket.
Elsewhere, an early tea has been called at Northants v Worcestershire and we still await the go-ahead for any play at all between Glamorgan and Gloucestershire in south Wales.
Durham 176-3 v Leicestershire - tea
Martin Emmerson
BBC Newcastle
David Bedingham’s luck eventually ran out when he was on 96 as he edged a Tom Taylor ball to Colin Ackerman at second slip.
He faced 139 balls and looked set for his first Durham hundred but cut a disconsolate figure as he walked off, missing out on what would have been his eighth century in first-class cricket.
His partnership with Alex Lees fell eight short of becoming Durham’s best third-wicket stand against Leicestershire. That record was set by Gordon Muchall and Mike Hussey here in 2005.
Tea is now being taken because it has begun to rain. Alex Lees will resume after the break on 62.
Nottinghamshire 197-1 v Lancashire
Ben Duckett is really enjoying himself against the spinners. A reverse sweep for four is followed by a square cut for another and the 'away side' are in sight of a first batting bonus point.
Duckett now has 73 to his name, with partner Ben Slater on 89. IT's been a tough day for Lancashire's bowlers so far.
Kent v Middlesex
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Prospects of any further play at Canterbury today are looking increasingly slim...
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Hampshire v Surrey 72-5
There's more than one way to play this batting lark - as Surrey are proving with a vital partnership at Arundel.
Laurie Evans and Jamie Smith have put on 36 and counting between them since Surrey slumped to 36-5 with a partnership that is giving the visitors some hope they can avoid a third successive defeat.
I say they have put on 36 between them - well, that's strictly true but Evans has walloped seven boundaries in a quickfire 34 while Smith has notched just one solitary off 33 deliveries.
More than one way to skin a cat, as they say.
Hannon-Dalby c Davies b Abell 0 (Warks 121 all out)
Just when Warwickshire thought they had seen off Craig Overton, it turns out Somerset had another trick up their never-ending magical bowling sleeve.
Tom Abell (pictured below) had not taken a wicket this summer but it seems the Somerset skipper should huck himself into the attack more often.
He gets last man Oliver Hannon-Dalby caught behind to wrap up the Bears' tail with fine figures of 3-4.
Can anyone stop Somerset? And are they trying to finish this as quickly as their two-day win over Northants?
Image source, Getty ImagesBedingham c Ackermann b Taylor 96 (Durham 176-3 v Leics)
Image source, Rex FeaturesWhat a pity - a century was there for the taking by David Bedingham, a South African with a UK passport, brought in by Durham for this season.
After hitting two sixes and 11 fours, he tries to drive a ball from Tom Taylor but edges to second slip where Colin Ackermann takes a smart catch by his left knee.
Bedingham's downfall ends a stand of 159 with Alex Lees, who is 62 not out - and we now have a rain hold-up at Grace Road as well. An early tea will be taken.
There will be no play before tea at Canterbury where continual rain means the earliest Middlesex can restart their innings of 22-1 against Kent is 16:00 BST.
There has been no play at all at Glamorgan but a pitch inspection is due at 15:45 BST for their game against Gloucestershire.
Meanwhile at Northampton, there's no sign of an imminent resumption between Northants and Worcestershire, with the latter languishing on 93-5.
Brookes c Hildreth b Abell 11 & Miles c Davies b Abell 0 (Warks 113-9)
Tim Bresnan is still battling away - but it's not so good at the other end for Warwickshire.
In fact it's probably the death knell for their innings as Somerset skipper Tom Abell snaffles a rare brace of wickets with his occasional medium pace.
Henbry Brookes edges to slip and Craig Miles is caught behind for a second-ball duck. A couple of what you might call your typical tail-end shots.
Yorkshire 131-4 v Derbyshire
Glorious by Dawid Malan, who brings up his fifty with an off-drive off pace bowler Dustin Melton. So impressed was he with the timing of that stroke that he trots down the pitch after it as the ball rolls towards the boundary.
It has taken the England left-hander 87 balls and it's quite a way to mark your home red-ball debut for your new(ish) county.