Leaders Surrey go to bottom side Worcs
Surrey could seal title this week
Strugglers Yorkshire and Lancashire meet in Roses match
Hampshire (5th) v Somerset (2nd); Notts (3rd) v Essex (4th)
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Lyth c Vilas b Bailey 16 (Yorks 32-3 v Lancs)
A third wicket for Lancashire - and a second for Tom Bailey.
And an unhappy Adam Lyth departs, to the very thinnest of edges.
The Yorkshire opener clearly did not think he hit that. And the video footage does not make it any clearer.
Azhar lbw Holland 12 (Hampshire v Somerset 45-2)
It's an inspired decision from Hampshire skipper James Vince as Ian Holland makes a breakthrough with the ball.
He traps Azhar Ali lbw for 12 - the Pakistan batsman plonks his front foot down and there's no movement on the delivery.
Somerset are 45-2 with James Hildreth joining Ben Green at the crease.
Hampshire v Somerset 43-1
Ben Green and Azhar Ali are keeping second-placed Somerset ticking along after the early loss of Marcus Trescothick at the Ageas Bowl.
Hampshire have brought Ian Holland into their bowling attack.
Brook c Vilas b Bailey 3 (Yorks 23-2 v Lancs)
A second wicket for Lancashire in the Roses Match as Harry Brook feathers a catch off Tom Bailey to keeper Dane Vilas.
Wickets in successive overs after Graham Onions' initial breakthrough. And this is a big one. Bailey's 50th of the season!
Notts 25-2 v Essex
Ben Slater finds consecutive boundaries at the end of Jamie Porter's over to push Notts to 25-2.
Porter is going for four an over, but with two wickets to his name I'm sure Essex won't care too much about his economy.
At the other end Matthew Quinn has just bowled his second maiden, with new Notts batsman Ben Duckett easing his way into the game.
Mitchell c Burns b Dernbach 13 (Worcs 22-1)
Image source, Getty ImagesJade Dernbach makes the big breakthrough at New Road as stand-in skipper Daryl Mitchell departs for 13, in the ninth over of the day.
Raval b Onions 8 (Yorkshire 20-1)
First blood in the Roses Match as Graham Onions gets one through Jeet Raval to rearrange his stumps.
Big LBW shout against Harry Brook first ball.
Tom Bailey has conceded just three runs off his first five overs (three of which have been maidens), but Onions, although having so far gone for 18, has looked the great threat.
Libby b Porter 9 (Notts 16-2 v Essex)
Jake Libby is bowled by Jamie Porter for nine and Notts are 16-2!
It's a bit of Trent Bridge swing that does the trick, with the ball knocking back off stump. Ben Duckett is next in.
That's Porter's second wicket, while credit must also go to Matthew Quinn who's holding down the other end effectively for Essex.
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First wicket of the day in Division Two came in the Leicestershire-Warwickshire game at Grace Road, where Bears left-armer Keith Barker had Harry Dearden caught behind for the leaders by Tim Ambose.
But Craig Miles wasn't far behind for Gloucestershire at Sophia Gardens, where he had Glamorgan opener Connor Brown leg before wicket.
And Tony Palladino was first to strike for Derbyshire against Northants at Wantage Road, getting Luke Procter LBW for 1.
Of all the opening partnerships in Div Two, Sam Robson and Nick Gubbins are the only two so far unparted for Middlesex against Kent on 23-0.
Meanwhile, at Chester-le-Street, where the Durham-Sussex game is yet to start, the word is that the light’s improving slightly. A further inspection was due from umpires Jeremy Lloyds and Paul Pollard at 11.00.
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Hampshire v Somerset 30-1
Dale Steyn and Kyle Abbott bowling for fifth place Hampshire, who aren't quite safe from relegation yet.
Somerset, meanwhile, are 43 points behind leaders Surrey and realistically need to win in Southampton this week to keep their faint title hopes alive.
Notts 14-1 v Essex
Ben Slater and Jake Libby move Notts onto 14-1 at Trent Bridge following the second-ball wicket of Kraigg Brathwaite.
In terms of team news Essex have made four changes, with India opener Murali Vijay making his debut, while Notts have given a debut to 19-year old Lyndon James, who replaces Matt Milnes.
Luke Fletcher returns for the hosts, with Harry Gurney nursing a slight calf injury.
Trescothick c Alsop b Abbott 15 (Hampshire v Somerset 17-1)
Kyle Abbott gets his revenge on Somerset opener Marcus Trescothick, who is out for 15 after edging behind to Tom Alsop.
The wicket comes after he comes around the wicket, and Trescothick turns and walks before the umpire even gives the decision.
The ball certainly moved away a bit there - Somerset 17-1 against Hampshire with Azhar Ali in to bat.
Yorkshire 9-0 v Lancashire
Tidy start for Yorkshire's openers Adam Lyth and Jeet Raval in the Roses Match at Headingley.
Two maidens for Tom Bailey, but Lyth has already despatched fellow former England man Graham Onions for two boundaries.
After making his Yorkshire debut against Notts at Trent Bridge last week, it's a home debut for New Zealander Raval.
Hampshire v Somerset 15-0
Second-placed Somerset are off to a flyer in Southampton.
Marcus Trescothick gets three boundaries in four balls off Hampshire's Kyle Abbott, who concedes 15 runs off his first over.
Somerset have made one change to their side, Josh Davey coming in for spinner Dom Bess.
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Worcestershire 2-0, v Surrey
Worcestershire captain Daryl Mitchell gets the first runs of the day at Worcester off Jade Dernbach's first over - followed by a maiden from Tom Curran.
Mitchell, who won the toss, is back in charge as county captain Joe Leach has been joined on the sidelines by stand-skipper Brett D'Oliveira, who has a back injury.
His opening partner is Tom Fell, with debutant Ollie Westbury due in at No 3.
Alex Milton keeps wicket in the absence of Ben Cox. And the Pears have also opted to bring in spinner Ben Twohig.
Every ball covered
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The action on 5 live sports extra comes from the Oval, where England and Alastair Cook are looking to build a lead against India in the fifth Test.
Brathwaite lbw Porter 0 (Notts 0-1 v Essex)
Kraigg Brathwaite has gone to just the second ball of the match!
Notts chose to bat and are already one down, Jamie Porter trapping the West Indies opener lbw for a duck.
Jake Libby is in and the hosts are 0-1 against Essex.
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The outlook for day one looks largely fine.
We may have sunny spells for now but cloud and rain will spread across many northern parts of the UK later, with drier and brighter conditions to the south. It's going to be a breezy one too.
A reminder that today's matches start at 10:30 BST because of the darker September nights.
Eight of our nine matches are set to start on time, with bad light at Chester-le-Street delaying the toss between Durham and Sussex.
Division One
Hampshire v Somerset - Somerset win toss & bat
Nottinghamshire v Essex - Notts win toss & bat
Worcestershire v Surrey - Worcs win toss & bat
Yorkshire v Lancashire - no toss, Yorkshire batting
Division Two
Durham v Sussex - start delayed, bad light.
Glamorgan v Gloucestershire - no toss, Glamorgan batting
Leicestershire v Warwickshire - no toss, Leicestershire batting
Middlesex v Kent - no toss, Middlesex batting
Northamptonshire v Derbyshire - no toss, Northants batting
Worcestershire have suffered a double injury blow on the overseas player front.
Indian spinner Ravichandran Ashwin will be kept out of their scheduked final two games by the groin injury which kept him out of the final Test at The Oval.
The Pears have also been denied the services of New Zealand international Martin Guptill, who was with them in the group stages, returning for T20 Blast Finals Day this Saturday.
He picked up a hamstring injury on Caribbean Premier League with the Barbados Tridents.
Wayne Parnell is their one allotted overseas player in this week's Championship game against Surrey. But the Pears are still looking at a potential overseas replacement for Finals Day.
Former skipper Daryl Mitchell captains the side in the absence of the injured Brett D'Oliveira, while Alex Milton keeps wicket in place of Ben Cox.
Champions elect Surrey are further strengthened today by having England's Ollie Pope available to play at New Road.