Essex's Harmer takes five wickets; Cook passes 50
Lancs' Buttler & Hameed out cheaply
Duckett scores 89-ball century
Stokes out for a duck for Durham
Fifties for Surrey's Roy, Burns & Sangakkara
Essex v Middlesex 231-9
Simon Harmer is on fire. The off-spinner claims a five-wicket haul in the first-innings - and with a pink ball no less.
Tim Murtagh is struck on the pads, and Middlesex's innings - which was once looking healthy - is now going out with a whimper.
Harmer took 14 wickets in last week's win against Warwickshire don't forget. Wow.
Division Two update
Teenage paceman Josh Tongue has finally broken Durham's last-wicket pair, removing Chris Rushworth for 30. The 19-year-old finishes with 4-41.
Notts all-rounder Steven Mullaney has just taken two wickets in two balls to leave Kent 173-9, but Mitch Claydon survived the hat-trick delivery. Daniel Bell-Drummond (77*) looks as though he'll carry his bat.
Image source, Getty ImagesSussex's Luke Wright (88 not out) is closing in on a century, with his side 219-4.
Northants have just lost four wickets for a single run to leave them seven down, Max Holden is still battling on 63.
It's been a slow old day at the Swalec so far - Derbyshire are 141-4 off 53 overs.
Essex v Middlesex 225-8
It's not just Paul Stirling in a hurry it seems... Ollie Rayner doesn't hang around for long - just two balls in fact - as he falls to the same combination of Simon Harmer and Ryan ten Doeschate.
Middlesex undoing all their earlier good work here.
Harmer now has 4-70.
Allow Twitter content?
This article contains content provided by Twitter. We ask for your permission before anything is loaded, as they may be using cookies and other technologies. You may want to read Twitter’s cookie policy, external and privacy policy, external before accepting. To view this content choose ‘accept and continue’.
BBC Sport app users may need to click the link to view this tweet.
Warwickshire v Lancashire 172-5
Stephan Shemilt
BBC Sport at Edgbaston
These round of matches are being played for the benefit of England players that will take part in day-night Tests, but a sub-plot is any increased interest from punters.
As we head into the evening, there's no noticeable swelling of the Edgbaston crowd, but it is free entry for the final session.
Essex v Middlesex 225-7
Image source, Rex FeaturesAll good things come to an end, and so it is with regret that I inform you that Paul Stirling's T20 innings has come to a close after 50 thrilling balls.
He's been caught by grateful Essex skipper Ryan ten Doeschate at cover from the bowling of Simon Harmer, who just keeps on picking up wickets.
Warwickshire v Lancashire 172-5
Shivnarine Chanderpaul just keeps on going. The veteran West Indian has another half-century and in good time too, off just 64 balls.
He has Ryan McLaren for company and is going well, moving up to 62 not out following the flurry of wickets in the other Division One games.
Hampshire 132-4 v Somerset
They just keep falling. Hampshire captain George Bailey goes, caught by Craig Overton off Tim Groenewald's seam-up stuff.
Somerset have fought back well in this session after they went wicketless in the opening one.
Yorkshire v Surrey 222-3
Big wicket at Headingley! Jack Brooks traps Jason Roy lbw to halt the runaway train.
Nevertheless he scored 87 from just 91 balls in a classic Roy innings to put his side in a wonderful position.
Kumar Sangakkara comes in. Not a bad replacement in my book.
Image source, Rex FeaturesEssex v Middlesex 219-6
But... he's lost his batting partner.
Ryan Higgins falls to Simon Harmer for a not particularly pretty six runs from 28 balls. Paul Stirling might run out of partners at this rate, with Middlesex still well short of a competitive first-innings total.
Essex v Middlesex 219-5
Image source, Rex FeaturesYep, Paul Stirling is definitely in a rush.
He has just smashed two sixes and a four off Paul Walter's bowling to move up to 71 not out from just 46 balls!
Division Two update
Barry McCarthy and Chris Rushworth are frustrating Worcestershire. Durham's last-wicket pair have put on 33 so far to take the hosts to 180-9.
Kent have just lost a seventh wicket at Trent Bridge - Steven Mullaney getting Adam Rouse for 22. Daniel Bell-Drummond is still there on 71, Kent are 163-7.
A couple more batsmen have also passed fifty, Sussex's Luke Wright is up to 74 and Northants' Max Holden is on 60.
Image source, Getty ImagesWarwickshire v Lancashire 151-5
Big Boyd Rankin strikes! Feels like a good old while since that phrase was last used, but the Warwickshire seamer has taken a really important wicket at Edgbaston.
He has Dane Vilas caught behind by Tim Ambrose to end a 96-run stand with Shiv Chanderpaul.
Yorkshire v Surrey 217-2
Image source, Rex FeaturesThe runs are flowing at Headingley, with Jason Roy (83 not out from 84 balls) and Rory Burns (71 not out) really taking it to the Yorkshire attack.
Their partnership is worth 142 runs and they've been scoring at just under a run per ball for the last 10 overs.
#bbccricket
The Patio Cricketers: Seems to be a very negative feeling towards day/night games. Allows more people to watch. Really worth giving it time I think.
Image source, Rex FeaturesEssex v Middlesex 194-5
Paul Stirling is not hanging around. The Irishman reaches his fifty from just 34 balls to give him a T20-esque strike-rate of 147.
It's counter-attacking stuff, with six fours and two sixes so far. Middlesex need him to keep it up and make post a similar score to his maiden County Championship hundred of 111 last time out against Yorkshire.
Northants 186-3 v Leicestershire
Alex Winter
BBC Radio Northampton sport
Leicestershire have bowled much better since the interval and, having removed Ben Duckett for just 12 more to his tea score, controlled the scoring rate. Max Holden has brought up fifty in stark contrast to Duckett - three times the number of deliveries and three times fewer boundaries. Smart knock nonetheless.
I'm prepared to say the crowd is slightly up on the number that would be in midway through a normal Championship day in midweek but still a long way short of the numbers that came to the One-Day Cup matches earlier in the season.
It's a very pleasant sunny late afternoon and a good night to sit with a drink or two - but equally one or two are going to miss the final session to catch the last bus home!
Yorkshire v Surrey 197-2
Mark Church
BBC Radio London commentator
Jason Roy (73 not out) and Rory Burns (63 not out) have taken this first day by the scruff of the neck.
Roy has played powerfully and Burns has shown patience as both batsmen have moved past fifty.
Roy has hit Adil Rashid for a couple of sixes and the partnership is moving Surrey into a strong position before the lights come on.
Hampshire 112-3 v Somerset
Liam Dawson is gone. Lewis Gregory raps his pads with a ball that kept low and the umpire's finger goes up to send him on his way and end his 139-ball stay.
Captain George Bailey joins former skipper James Vince in the middle.
Warwickshire v Lancashire 119-4
As expected, Shiv Chanderpaul and Dane Vilas are most definitely the men for a fight.
Warwickshire had Lancashire 55-4 earlier and looked in control, but the experienced duo are putting the breaks on. Chanderpaul has 41, Vilas has 18 and their partnership is worth 64.
Yorkshire v Surrey 179-2
He may be his England team mate, but that doesn't stop Jason Roy, who launches into Adil Rashid into the Headingley stands.
The Yorkshire legspinner's second over costs eight runs. Roy is into his work now - he's up to 63.