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Kookaburra balls being used in this round of games plus first round in July
D1: Lancashire, put in by leaders Surrey, rally from 119-5 to be bowled out for 274
Teams who won the toss batting first in all the other games
D1: Essex duo Dan Lawrence and Tom Westley hit tons at home to Warwickshire
D1: Nick Gubbins & Liam Dawson going well for Hampshire against Middx
D1: Rob Keogh out for 97 for Northants against Kent in battle of bottom two
D1: Somerset bowled out for 163 at home to Nottinghamshire
D2: Alex Lees hits a ton as leaders Durham pile up a big score at Leicester
D2: Second-placed Sussex bowl out Glamorgan for 242
D2: Fin Bean makes a century for Yorkshire at home to Gloucestershire
D2: Pears opener Jake Libby still there but Pears four down at home to Derbyshire
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Leicestershire v Durham 113-0
Having seen his opening partner bring up his landmark, Alex Lees gets there.
His half-century has come at a slightly more sedate pace, off 72 balls, but it has put Durham in a commanding position before lunch.
Hampshire 66-2 v Middlesex
Another six from James Vince!
Josh de Caires is again the bowler who watches the ball head over the boundary rope.
That will frustrate de Caires who had been on for a maiden before Vince sent the final ball for six.
Lancashire 46-3 (19.2 overs) v Surrey
Surrey claim a third wicket of the morning as Lancashire skipper Keaton Jennings departs looking very unhappy with an LBW decision in the favour of Aussie paceman Sean Abbott.
The usually unflappable Jennings is not usually the sort to show any sort of emotion.
A second wicket in four overs for Abbott.
Durham 101-0 v Leicestershire
Martin Emmerson
BBC Radio Newcastle
Durham had 100 runs on the board in just over an hour - and Michael Jones has scored 57 of them.
It's a hot day and this was a good toss to win.
The forecast suggests it feels like about 34C. The outfield is really quick but there's also a really short boundary towards The Meet.
Durham are down in numbers because of injuries to bowlers. So they have brought Matt Parkinson, bound for Kent at the end of the season, back in on loan from Lancashire. He played one game for Durham, against Derbyshire, earlier in the season.
That means he is up against his twin brother Callum, who will join Durham next season. It's only the second time they have faced each other in a County Championship match.
Durham have also given a debut to New Zealander Ray Toole. The 25-year-old plays for Central Districts and featured for Essex in the one day cup last year. He's been playing for Paul Collingwood's club, Shotley Bridge, in the North East Premier League this season.
Hampshire 51-2 v Middlesex
They've had a few wobbles but Hampshire are safely negotiated past 50 thanks to some characteristically fine batting from James Vince.
He's scored 24 from 26 balls and sent Josh de Caires into the stands for the first six of the contest.
Leicestershire v Durham 100-0
The Division Two leaders are flying and bring up three figures inside 17 overs and after just 70 minutes of play.
Michael Jones (56) helps bring it up with back-to-back fours off Tom Scriven, while Alex Lees (42) is closing on his own half-century.
Glamorgan 46-3 (15 overs) v Sussex
Nick Webb
BBC Radio Wales
Sussex’s overseas pacemen had Glamorgan on the back foot in the first hour in sunny Cardiff despite the home side choosing to bat.
New Zealand’s Henry Shipley trapped Zain Ul Hassan lbw for 9 and Tom Bevan went the same way without scoring in only his second first-class match.
Sam Northeast started with three classy boundaries and did not look in trouble, but he then edged Aussie Nathan McAndrew to keeper Oli Carter for 17.
Andrew Salter, a stand-in opener again, found life difficult early on, and would be hoping that the Kookaburra ball being used for this round loses its shine as quickly as expected.
Leicestershire v Durham 95-0
The Durham openers have made hay in Leicester and it's Michael Jones who wins the race to fifty.
He's mixed attack with the odd bit of patience, smashing a six and 10 fours for his 46-ball half-century.
The visitors are going at around six an over - it could be a long, thankless day in the field for Leicestershire.
Lancashire 35-2 (13.1 overs) v Surrey
Surrey break through again as Josh Bohannon is trapped for 10.
Sean Abbott comes on as second bowling change for Surrey and, just as he did at Old Trafford in the first game of the season, he strikes with his first ball.
Dane Vilas comes in to join fit-again skipper Keaton Jennings, who is already on 21 in his comeback match after two months out with a bad hamstring injury.
Northamptonshire 44-3 v Kent
One captain dismissed by the other as Jack Leaning takes a catch to send Luke Procter on his way.
It's a carbon copy of Arshdeep Singh's previous dismissal with new skipper Leaning taking a simple catch at second slip.
Again, Singh had four slips in place and Procter didn't look comfortable in the crease as the delivery came in and ends-up edging softly behind.
You can see the immediate disappointment on his face, it was simple as that for Kent who are going along well against the bottom side.
Somerset 50-3 v Nottinghamshire
The hosts have got there at a decent lick in the 14th over, but it's not without damage.
Openers Sean Dickson and Tom Lammonby are already back in the hutch, followed by George Bartlett all sent there by Brett Hutton on a belting day for batting.
Work to do for the Toms - Abell and Cohler-Kadmore.
Somerset 48-3 v Nottinghamshire
Somerset are in a spot of bother as Brett Hutton strikes again.
George Bartlett leaves the first ball of Hutton's seventh over and will wish he hadn't.
It hits him above the knee roll and looks high, but the finger goes up and the Hitman has a third of the morning.
Hampshire 31-2 v Middlesex
They've escaped a couple of close calls but this time Joe Weatherley has to walk.
It's a short delivery form Tom Helm which Weatherley pulls to Luke Hollman at square leg.
He didn't seem to commit fully to the shot and it ends up being a simple catch and a disappointing way to go for the batter, having already survived being dropped earlier.
Hampshire 30-1 v Middlesex
A bit of mix-up between Joe Weatherley and Nick Gubbins almost sees the latter run out.
It seemed an unnecessary run to go for and it was hearts in mouths for a second but no direct hit from the fielder spares their blushes.
Weatherley was dropped earlier on so that's a couple of chances gone begging for Middlesex.
Somerset 43-2 v Nottinghamshire
A lifeline for George Bartlett who fishes at a Dane Patterson delivery.
It obligingly takes his outside edge, but Joe Clarke at first slip and Matt Carter at second leave the chance for one another and it flies through the gap for four.
Notts are on top so far.
Glamorgan 34-2 (9 overs) v Sussex
Two wickets in successive overs for New Zealander Henry Shipley on his Sussex debut against Glamorgan at Sophia Gardens.
The overseas stand-in for Cheteshwar Pujara has removed both Zain-ul-Hassan for and then Tom Bevan, on omly his second start for a third-ball duck.
Worcestershire 31-0 Derbyshire
Good start for Worcestershire at a beautifully sunny New Road.
Jake Libby won the toss and his decision to bat looks a good one so far as the boundaries have come along regularly with his opening partner Gareth Roderick.
Brett D'Oliveira is out with illness today and Jack Haynes is missing with a knee injury.
It's a big day for Pears youngster Rehaan Edavalath who makes his first-class debut.
Somerset 34-2 v Nottinghamshire
I think it's fair to say Brett Hutton is enjoying the Kookaburra.
He goes round the wicket for the first time and finds the outside edge of Tom Lammonby for his second scalp of the morning.
The opener had made a positive start with 24 off 31 balls, but is pouched well at first slip by Joe Clarke.
Leicestershire v Durham 59-0
Leicestershire have had an encouraging start to the Championship season, but have endured a turbulent week.
Head coach Paul Nixon was removed from post while Colin Ackermann, Chris Wright and Callum Parkinson all confirmed their departures at the end of the season.
To make matters worse, Durham have got off to an absolute flier here, with openers Alex Lees and Michael Jones in limited overs mode.
They have piled up 59 from just seven overs.
Essex 20-2 (5.1 overs) v Warwickshire
A second wicket for Warwickshire at Chelmsford as Hasan Ali gets in on the act.
This time it is the big one, Alastair Cook, who is also caught behind by Michael Burgess.
Dan Lawrence has come in to join the third of Essex‘s England batsmen Tom Westley.