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
Surrey 56-1 v Gloucestershire
Ryan Higgins has struck at The Oval.
Mark Stoneman is the Surrey batsman to fall, trapped lbw for 22. He'd looked in decent form, too, striking three boundaries as he and Ryan Patel shared a 50-run opening stand.
South Africa great Hashim Amla is the new man in.
Warwickshire 57-1 v Notts
For a side who got put in to bat, Warwickshire are going quite well against in-form Notts.
Skipper Will Rhodes is leading from the front, with seven fours in his 46 out of the Bears' 61-1.
Pieter Malan has so far been more reserved. Just three runs from 24 balls in his 42-minute stay at the crease.
Sussex 57-7 v Northants
Anything Lancashire can do, Northants can do better.
Wayne Parnell claims his second wicket of the morning, trapping Delray Rawlins in front for just two.
Sussex are in all kinds of trouble.
Essex 82-3 v Durham
Martin Emmerson
BBC Radio Newcastle
What a pleasure it is to see spectators in the stadium again.
It's 611 days since they last saw any action here in Chester-le-Street and that was in a rain-affected draw against Glamorgan. The last two days were lost to the weather so the members have been 'wintering well' since.
So this morning it was time to make up for matters missed and it was fantastic to see the ovation given to Durham's Chris Rushworth as he came out to warm up.
Rushworth has taken one of the three Essex wickets to fall this morning, with the visitors 82-3.
Yorkshire 35-6 v Lancashire
Young Yorkshire wicket-keeper Harry Duke has settled a few nerves in the away dressing room at Old Trafford.
Two early boundaries for the teenager, followed by an edged four for Jordan Thompson.
And they have at least got past Yorkshire's lowest first-class score in a Roses Match.
That remains the 33 they got skittled for at Headingley in 1924.
That was against a Yorkshire side containing famous old names like Holmes and Sutcliffe, Maurice Leyland and Wilfred Rhodes.
This Yorkshire batting line-up is nowhere near so strong. For varying reasons, Joe Root, Dawid Malan, Gary Ballance and Jonny Bairstow are all unavailable. But, even so, this has been an extraordinary morning in Manchester.
Sussex 55-6 v Northants
Tom Clark is bowled by Tom Taylor for 11 and Sussex are six down at Hove.
Only Clark and Tom Haines (13) have reached double figures for the hosts this morning.
Sussex 51-5 v Northants
Another Sussex wicket has fallen now!
Captain Ben Brown falls for nine, caught behind off Wayne Parnell, to leave Sussex 51-5.
What a morning Northants and Lancashire are having.
Kohler-Cadmore lbw Lamb 10 (Yorkshire 21-6 v Lancashire)
Good grief! Six down!
Danny Lamb gets in on the act as he traps Tom Kohler-Cadmore on the back foot.
Even allowing for the fact that Yorkshire were weakened by injury and unavailability, this sort of carnage was not anticipated.
Still another two runs need to equal their lowest ever first-class score - when they were bowled out for just 23 by Butch White, Derek Shackleton and Bob Cottam for Hampshire at Middlesbrough in 1965
Bess c Lamb b Wood 3 (Yorkshire 21-5 v Lancashire)
Dom Bess is next man to go at Old Trafford.
The Yorkshire and England spinner attempts to cut and Luke Wood has his first wicket.
The new man at the crease, in only his second first-class game, is wicketkeeper Harry Duke.
Kohler-Cadmore is still there on 10.
Worcestershire 62-3 v Notts
Dan Wheeler
BBC Radio Hereford & Worcester
Never run on a misfield.
Jack Haynes was the one with the fatal hesitation as he drove Dustin Melton to cover.
Matt Critchley's scrambled stop hoodwinked Haynes into thinking that a cheeky single might be on.
But a lightning throw which tickled the stumps at the bowler's end caught Jake Libby a couple of yards short.
Libby, who had looked in great touch, is gone for 26. Ouch.
Yorkshire 18-4 v Lancashire
Tom Kohler-Cadmore is put down for a second time in the morning session.
Luke Wells puts him down at first slip off Luke Wood, who so nearly marked his first over with a wicket.
Warwickshire 32-1 v Notts
Warwickshire, put in to bat by Nottinghamshire, lose their first wicket at Edgbaston.
Rob Yates, deputising as opener for England's Dom Sibley, goes for 8, bowled by first-change Lyndon James in his first over.
The new man in is South African Pieter Malan.
Essex 49-3 v Durham
And now Essex have lost number three Tom Westley to a 21-ball duck too.
After that quiet opening 15 minutes or so to the day there's been a clatter of wickets across the country ever since.
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’.
Sussex 30-4 v Northants
Three wickets in the space of two overs at Hove!
Sussex slip from 28-1 to 30-4, losing Tom Haine, Stiaan van Zyl and Australia's Travis Head in quick succession.
Ben Sanderson has figures of 3-16 for Northants.
Middlesex 33-0 v Leicestershire
Like Surrey - and very much unlike Yorkshire - Middlesex have also made good progress in the opening hour of their match against Leicestershire.
Sam Robson (17 not out) and Stevie Eskinazi (14 not out) remain untroubled.
Surrey 27-0 v Gloucestershire
Surrey have made a decent start against Gloucestershire - the only side other than the two Roses rivals still unbeaten - at The Oval.
Ryan Patel and Mark Stoneman have remained relatively untroubled, including seeing off in-form opening bowler Ryan Higgins.
Hill c Livingstone b Bailey 2 (Yorkshire 11-4 v Lancashire)
George Hill goes too, to the last ball of the 11th over.
A second wicket for Tom Bailey as he finds the Yorkshire youngster's edge - and Liam Livingstone takes a good slip catch.
Awful start for Yorkshire. Only the fifth time in their history that they have lost their first four wickets for less than 11 runs.
It's a fair bet that England spinner Dom Bess, who is the new man in, never previously envisaged that he would one day be batting before noon on the first morning of a Roses Match.
Tom Kohler-Cadmore does at least respond by caressing the first boundary of the day.
Essex 38-2 v Durham
Nick Browne has now fallen at Chester-le-Street too, bowled by Matthew Potts.
Tom Westley and Michael Pepper are the new men in.
Brook run out (Davies) 0 (Yorkshire 9-3 v Lancashire)
Harry Brook is run out after an awful mix-up.
Tom Kohler-Cadmore pushed for a shirt single on the off side, Brook was slow to respond - and was well short of his ground.
Worcestershire 37-2 v Derbyshire
Tom Fell's early fusillade of shots proved a little too much too soon.
He has now gone too, also to Sam Conners.
He nicked another cracker from Conners to wicketkeeper Brooke Guest just two balls after Leus du Plooy had dropped his second catch of the morning shin high at first slip off the luckless Sam Conners.
Jake Libby has now moved on to 25, while new man Jack Haynes has made a good start