It's been a frustrating day for several sides - but a productive day for a number of others.
Rain prevented Yorkshire and Lancashire resuming hostilities in the Roses match, but both have already secured a top two finish in Group Three.
The Durham-Notts game in Group One was washed out for the day too. That will suit leaders Notts, who only need to avoid defeat to progress to Division One.
Warwickshire still look favourites to join them from Group One. A draw is enough for them against local rivals Worcestershire - and they already look well on their way to that.
But defending champions Essex's hopes were ended by the Covid-related abandonment of their game against Derbyshire.
Group Two table-toppers Somerset took a big step towards progression too, posting 429 at the Kia Oval against Surrey.
The winner-takes-all game between Gloucestershire and Hampshire remains in the balance. But the visitors have the edge after a super 174-run opening stand between Joe Weatherley and Ian Holland.
We'll be back for more on Tuesday - please join us at 10:45 BST.
Close of play scores
Group One:
Derbyshire 146, Essex 86-3 (match abandoned)
Nottinghamshire 312-9 v Durham (no play on Monday)
Warwickshire 395, Worcestershire 152-2
Group Two:
Gloucestershire 229, Hampshire 270-5
Middlesex 324, Leicestershire 174-5
Somerset 429, Surrey 24-0
Group Three:
Northants 219, Glamorgan 52-2
Sussex 181, Kent 122-7
Lancashire 273-2 v Yorkshire (no play on Monday)
Close of play at Cheltenham
Glos 229 v Hants 270-5
Ooh, the last ball of the day from Matt Taylor is played and missed by Lewis McManus, but he gets away with it.
That perhaps sums up a day that has belonged to Hampshire, who made short work of the Gloucestershire tail from 214-6 to 229 all out this morning.
Joe Weatherley and Ian Holland then put on 174 for Hampshire's opening stand and while they've lost a few wickets since, the visitors lead by 41 with five more batsmen to come.
With the winner progressing to the six-team Division One format and the loser having to settle for Division Two, this is going to be a thriller over the next couple of days.
Post update
Glos 229 v Hants 270-5
Nick Gubbins takes a single and it will be up to wicketkeeper Lewis McManus to see out the final three balls of the day.
Post update
For a moment they thought they had a wicket but Nick Gubbins' shot did not carry to Ollie Price.
Post update
Glos 229 v Hants 269-5
The final over of the day on the way.
Tom Price just bowled a maiden, his third in 11 overs.
Can Gloucestershire break this stand of 37 runs?
Post update
Glos 229 v Hants 269-5
Lewis McManus is getting in on the act now.
He hits Tom Price for successive boundaries to move on to 14no.
The lead is 40. Hampshire, after that wobble, are back in command.
Four overs to go at Cheltenham
Glos 229 v Hants 260-5
Another boundary and a single from Nick Gubbins takes him on to 29.
This has been an excellent example of a first-class innings - patient before gradually opening up, aware of his side's situation in the match at all times.
The lead is now 31. Four overs remaining for the day.
Close of play at New Road
Warwickshire 375, Worcestershire 152-2
Just one game left on now today as the players troop off in the Midlands derby at New Road.
Daryl Mitchell (83) and Jack Haynes (42) have so far put on 79 for the third wicket to steer Worcestershire to 152-2, an overnight deficit of 243 on first innings.
New Zealand spinner Ish Sodhi cleaned up the tail to take 6-89 on his Pears debut, but this game already looks to be heading for a draw, unless the Bears can grab some quick wickets on this flat track tomorrow.
Eight overs remaining at Cheltenham
Glos 229 v Hants 251-5
The new ball cost Hampshire a couple of wickets but Nick Gubbins appears to be relishing it.
Another boundary from that over and having taken an hour and a half to get past 10, he's now motoring at 22.
Lewis McManus is also off the mark with a boundary.
The lead building now, 22. Five wickets left and eight overs remaining today.
Post update
Glos 229 v Hants 241-5
Nick Gubbins has been a patient man today - before the past over, his 10 runs had taken 70 deliveries to accumulate.
But with those couple of wickets, he now has the air of a man who knows the run rate needs to be upped to build a lead.
He hits Ryan Higgins for a couple of boundaries from the innings' 84th over and Hampshire lurch 12 ahead.
Five overs left at New Road
Bears 375, Pears 139-2
Daryl Mitchell is nearing a first century of the season, on 78.
Jack Haynes is nearing a half-century, on 35.
And the day is nearing an end. Just five overs left now.
But how near are Warwickshire to a third Worcestershire wicket?
Close of play at Merchant Taylors'
Middlesex 324, Leicestershire 174-5
Official confirmation. No more play today at Merchant Taylors'.
Leicestershire will resume tomorrow with Colin Ackermann on 65 - and Ben Mike on 1.
Hampshire, of course, are actually in the lead here.
This one is going to come down to how big a first-innings lead they can build.
Anything above 50 will be useful.
De Grandhomme c O Price b Higgins 0
Glos 229 v Hants 232-5
A fifth-ball duck for Colin De Grandhomme.
A third wicket for Ryan Higgins (3-33) as Ollie Price takes a second catch at slip.
Wasn't as good as the one a couple of minutes ago but few will be.
Openers Joe Weatherley and Ian Holland will not be happy men in the pavilion - the hard work of their 174-run partnership is being somewhat wasted here.
Prest c O Price b Worrall 18
Glos 229 v Hants 229-4
What. A. Catch.
You won't see many better grabs in the slips than this.
Tom Prest's edge is virtually past Ollie Price by the time he can react - but he still manages to leap to his right and snaffle a stunning one-handed catch.
The scores are level. But Hampshire have six wickets in hand of course.
There are only two games going on anywhere in the country and, with just a few minutes to go before the Worcester Cathedral bells chime six o' clock, one of them is thankfully at picturesque New Road.
With 12 overs left in the day, Daryl Mitchell has moved on to 74, his season's best score, after putting on 50 so far for the third wicket with Jack Haynes (24).
Post update
Glamorgan spinner Andrew Salter claims four for 18 as Northamptonshire are bowled out for 215.
Hampshire haven't exactly shut up shop at Cheltenham but they are taking no chances. Their past 30 runs have taken more than an hour.
It's a delicate balancing act, though - to progress to the six-team Division One and have a chance of the County Championship title, they have to win this match.
A draw is not enough.
Off for bad light at Merchant Taylors'
Middlesex 324, Leicestershire 174-5
Umpires Mark Newell and Ben Debenham have checked their light meters - and they've gone off for bad light in the Middlesex-Leicestershire game.
There are still 17 officially overs to be bowled tonight - but a storm is due and the suggestion is that they are unlikely to return to the middle this evening.
The covers are waiting to be rolled/dragged on.
Visiting skipper Colin Ackermann is on 65, having led a Leicestershire rearguard action that has nudged the Foxes to within 150 of Middlesex's all-out total of 324.
Live Reporting
Ged Scott and Michael Beardmore
All times stated are UK
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Latest PostGood night - see you tomorrow
It's been a frustrating day for several sides - but a productive day for a number of others.
Rain prevented Yorkshire and Lancashire resuming hostilities in the Roses match, but both have already secured a top two finish in Group Three.
The Durham-Notts game in Group One was washed out for the day too. That will suit leaders Notts, who only need to avoid defeat to progress to Division One.
Warwickshire still look favourites to join them from Group One. A draw is enough for them against local rivals Worcestershire - and they already look well on their way to that.
But defending champions Essex's hopes were ended by the Covid-related abandonment of their game against Derbyshire.
Group Two table-toppers Somerset took a big step towards progression too, posting 429 at the Kia Oval against Surrey.
The winner-takes-all game between Gloucestershire and Hampshire remains in the balance. But the visitors have the edge after a super 174-run opening stand between Joe Weatherley and Ian Holland.
We'll be back for more on Tuesday - please join us at 10:45 BST.
Close of play scores
Group One:
Derbyshire 146, Essex 86-3 (match abandoned)
Nottinghamshire 312-9 v Durham (no play on Monday)
Warwickshire 395, Worcestershire 152-2
Group Two:
Gloucestershire 229, Hampshire 270-5
Middlesex 324, Leicestershire 174-5
Somerset 429, Surrey 24-0
Group Three:
Northants 219, Glamorgan 52-2
Sussex 181, Kent 122-7
Lancashire 273-2 v Yorkshire (no play on Monday)
Close of play at Cheltenham
Glos 229 v Hants 270-5
Ooh, the last ball of the day from Matt Taylor is played and missed by Lewis McManus, but he gets away with it.
That perhaps sums up a day that has belonged to Hampshire, who made short work of the Gloucestershire tail from 214-6 to 229 all out this morning.
Joe Weatherley and Ian Holland then put on 174 for Hampshire's opening stand and while they've lost a few wickets since, the visitors lead by 41 with five more batsmen to come.
With the winner progressing to the six-team Division One format and the loser having to settle for Division Two, this is going to be a thriller over the next couple of days.
Post update
Glos 229 v Hants 270-5
Nick Gubbins takes a single and it will be up to wicketkeeper Lewis McManus to see out the final three balls of the day.
Post update
For a moment they thought they had a wicket but Nick Gubbins' shot did not carry to Ollie Price.
Post update
Glos 229 v Hants 269-5
The final over of the day on the way.
Tom Price just bowled a maiden, his third in 11 overs.
Can Gloucestershire break this stand of 37 runs?
Post update
Glos 229 v Hants 269-5
Lewis McManus is getting in on the act now.
He hits Tom Price for successive boundaries to move on to 14no.
The lead is 40. Hampshire, after that wobble, are back in command.
Four overs to go at Cheltenham
Glos 229 v Hants 260-5
Another boundary and a single from Nick Gubbins takes him on to 29.
This has been an excellent example of a first-class innings - patient before gradually opening up, aware of his side's situation in the match at all times.
The lead is now 31. Four overs remaining for the day.
Close of play at New Road
Warwickshire 375, Worcestershire 152-2
Just one game left on now today as the players troop off in the Midlands derby at New Road.
Daryl Mitchell (83) and Jack Haynes (42) have so far put on 79 for the third wicket to steer Worcestershire to 152-2, an overnight deficit of 243 on first innings.
New Zealand spinner Ish Sodhi cleaned up the tail to take 6-89 on his Pears debut, but this game already looks to be heading for a draw, unless the Bears can grab some quick wickets on this flat track tomorrow.
Eight overs remaining at Cheltenham
Glos 229 v Hants 251-5
The new ball cost Hampshire a couple of wickets but Nick Gubbins appears to be relishing it.
Another boundary from that over and having taken an hour and a half to get past 10, he's now motoring at 22.
Lewis McManus is also off the mark with a boundary.
The lead building now, 22. Five wickets left and eight overs remaining today.
Post update
Glos 229 v Hants 241-5
Nick Gubbins has been a patient man today - before the past over, his 10 runs had taken 70 deliveries to accumulate.
But with those couple of wickets, he now has the air of a man who knows the run rate needs to be upped to build a lead.
He hits Ryan Higgins for a couple of boundaries from the innings' 84th over and Hampshire lurch 12 ahead.
Five overs left at New Road
Bears 375, Pears 139-2
Daryl Mitchell is nearing a first century of the season, on 78.
Jack Haynes is nearing a half-century, on 35.
And the day is nearing an end. Just five overs left now.
But how near are Warwickshire to a third Worcestershire wicket?
Close of play at Merchant Taylors'
Middlesex 324, Leicestershire 174-5
Official confirmation. No more play today at Merchant Taylors'.
Leicestershire will resume tomorrow with Colin Ackermann on 65 - and Ben Mike on 1.
Post update
Hampshire, of course, are actually in the lead here.
This one is going to come down to how big a first-innings lead they can build.
Anything above 50 will be useful.
De Grandhomme c O Price b Higgins 0
Glos 229 v Hants 232-5
A fifth-ball duck for Colin De Grandhomme.
A third wicket for Ryan Higgins (3-33) as Ollie Price takes a second catch at slip.
Wasn't as good as the one a couple of minutes ago but few will be.
Openers Joe Weatherley and Ian Holland will not be happy men in the pavilion - the hard work of their 174-run partnership is being somewhat wasted here.
Prest c O Price b Worrall 18
Glos 229 v Hants 229-4
What. A. Catch.
You won't see many better grabs in the slips than this.
Tom Prest's edge is virtually past Ollie Price by the time he can react - but he still manages to leap to his right and snaffle a stunning one-handed catch.
The scores are level. But Hampshire have six wickets in hand of course.
50 stand for Mitchell and Haynes
Bears 375, Pears 123-2
There are only two games going on anywhere in the country and, with just a few minutes to go before the Worcester Cathedral bells chime six o' clock, one of them is thankfully at picturesque New Road.
With 12 overs left in the day, Daryl Mitchell has moved on to 74, his season's best score, after putting on 50 so far for the third wicket with Jack Haynes (24).
Post update
Glamorgan spinner Andrew Salter claims four for 18 as Northamptonshire are bowled out for 215.
Glamorgan's Salter has Northants in a spin
Glamorgan spinner Andrew Salter claims four for 18 as Northamptonshire are bowled out for 215, Glamorgan reach 52 for two before rain.
Read morePost update
Glos 229 v Hants 224-3
Hampshire haven't exactly shut up shop at Cheltenham but they are taking no chances. Their past 30 runs have taken more than an hour.
It's a delicate balancing act, though - to progress to the six-team Division One and have a chance of the County Championship title, they have to win this match.
A draw is not enough.
Off for bad light at Merchant Taylors'
Middlesex 324, Leicestershire 174-5
Umpires Mark Newell and Ben Debenham have checked their light meters - and they've gone off for bad light in the Middlesex-Leicestershire game.
There are still 17 officially overs to be bowled tonight - but a storm is due and the suggestion is that they are unlikely to return to the middle this evening.
The covers are waiting to be rolled/dragged on.
Visiting skipper Colin Ackermann is on 65, having led a Leicestershire rearguard action that has nudged the Foxes to within 150 of Middlesex's all-out total of 324.