Stuart Broad and James Anderson on opposite sides as Notts bowl out Lancashire for 214.
Surrey's Gus Atkinson takes 6-68 - his first five-for - for 2022 champions against Essex.
Second-placed Hampshire all out for 229 on day one against Warwickshire.
Australia batter Steve Smith makes debut for Sussex at New Road
Jonny Bairstow takes three catches behind stumps for Yorkshire against Glamorgan.
On-loan paceman Henry Brookes takes 6-20 on debut for Derbyshire.
Hampshire 217-9 v Warwickshire
Another soft dismissal. A swivelling Kyle Abbott pulls a short one off Ed Barnard to Chris Rushworth at fine leg to break another promising partnership with James Vince.
Mohammad Abbas is the new man in the middle.
Derbyshire 77-0 v Leics 122
Derbyshire could not have asked for much more on day one against Leicestershire.
Their deficit is under 50 now and they still haven't lost a wicket, with Harry Came and Haider Ali progressing nicely as the tea break approaches.
Notts 18-2 v Lancs 214
Will Williams has Haseeb Hameed in all sorts of trouble in his first over, which is a maiden.
Quote MessageAn encouraging over, that. There's a lot of pressure when you're replacing James Anderson and Will Williams has sent down a very good first over.
Scott Read, BBC Radio Lancashire
Somerset v Northamptonshire 137-4
The umpires had been out, the covers were coming off and there was hope of a re-start at the County Ground but, guess what, just when everything was looking rosy, the rain began again.
The covers are coming back on and, looking at the radar, it'll be a while before we see any cricket in Somerset.
Yorkshire v Glamorgan 199-8
Billy Root is the latest Glamorgan batter to fall to Mickey Edwards. It's a fairly tame shot to the sub fielder Jonny Tattersall at point.
Essex 204-3 v Surrey
Image source, Getty ImagesAn excellent session for Essex, who have added 104 to their lunchtime score for the loss of Dan Lawrence.
He fell cheaply to Sean Abbott, but Matt Critchley and Tom Westley have added exactly 100 in 30 overs since then.
Westley is 53 not out and the more aggressive Critchley - who hit two sixes off spinner Cameron Steel - has 57.
Notts 18-2 v Lancs 214
When Tom Bailey isn't taking wickets, he's certainly asking questions of the Nottinghamshire batting line-up.
There's a big appeal for a catch behind but Matthew Montgomery and the umpires are unmoved.
Will Williams comes on to replace James Anderson at the other end and his first ball is a booming outswinger. Who does that remind you of?
Worcestershire 264 v Sussex
Ged Scott
BBC Sport at New Road
The final two Worcestershire wickets go down in the space of three balls - and tea is taken.
What is the betting on Steve Smith, due to bat five, having his first bat for Sussex before the close of play tonight?
It has so far been Ollie Robinson‘s day. Three more wickets in just seven balls to add to his four in the morning session. 7-59, his best figures for two years.
But a good effort by several Pears with the bat - half-centuries for Adam Hose, 59 on his home debut, and 59 also from Matthew Waite, who shared a century stand of 103 in 14 overs with Joe Leach (53).
The only concern is the skies overhead. Bad stuff is forecast - and it certainly looks to be building up a bit,
Hampshire 199-8 v Warwickshire
James Vince is clearly getting some T20 practice in before the Blast returns...
He picks one up off a length from Oliver Hannon-Dalby to clip over the deep mid-square leg boundary with consumate ease to move to 58.
Cue two Bears fielders being sent out to defend the ropes. One swipe is all it took...
A batting bonus point is not out of the question with a few more lusty blows like that.
Worcs 264 v Sussex
And just like that, the Worcestershire innings is over.
Ollie Robinson ends it as he began with a rapid haul of wickets.
He has Joe Leach caught at second slip by Steve Smith for 53 and two balls later traps Ben Gibbon in front for figures of 7-59.
Just one batting point for the home side but they will settle for that after their top order was skittled by Robinson during the morning.
Notts 14-2 v Lancs 214
James Anderson takes a comfortable catch at square leg and Tom Bailey has another, Ben Slater the batter to fall.
Twelve wickets have fallen at Trent Bridge and we've only just passed the halfway point on day one.
Essex 200-3 v Surrey
Matt Critchley has started this season very well indeed and reaches his fifth 50 from 85 balls by opening the face and running a ball from Sean Abbott down to third man for his fifth boundary, to go with two sixes. Just one wicket for Surrey so far in this season.
Derbys 54-0 v Leics 122
Haider Ali and Harry Came post a 50 partnership and anyone looking at the match position might think they are not playing on the same pitch that Leicestershire batted on.
Rest assured, they are, but the Derbyshire openers are underscoring the good worth done by their bowlers.
Yorkshire v Glamorgan 174-7
One of the worst feelings as a batter - leaving the ball and then hearing the clatter of stumps behind you.
Well, it's just happened to Michael Neser.
Mickey Edwards gets his second wicket of the innings.
Hampshire 186-8 v Warwickshire
Oh dear, oh dear. James Fuller sets off as soon as he cracks that delivery off Oliver Hannon-Dalby towards Will Rhodes at mid-off.
He only had a stump-and-a-half to aim at and he had to hit it direct, but Rhodes does the business with Fuller's dive to make his ground in vain.
Needless, kamikaze stuff in the circumstances and the 49-run partnership is over. Fuller had played nicely for his 27 from 33 balls, with five fours.
Kyle Abbott joins James Vince.
Hampshire 186-7 v Warwickshire
James Vince prods to mid-on for a single to bring up his 47th first-class half-century.
It has come from 72 balls with seven fours, many of them oozing with typical Vincian class.
This has been a captain's innings too, keeping his head while the wickets tumbled around him, scoring from the bad balls and dealing with the good ones as best he can.
Worcs 263-8 v Sussex
Image source, Getty ImagesEnough is enough. Sussex call up their best bowler, Ollie Robinson, and the England paceman completes a five-for by bowling Matthew Waite for 59 - made from just 54 balls.
Waite put on 103 with Joe Leach, a stand which has transformed their innings after Robinson took four wickets with the new ball to reduce them to 44-5.
Essex 195-3 v Surrey
Tom Westley posts a 127-ball half-century with the help of an inside edge off Sean Abbott which runs away fine for four.
It's his fifth boundary so far and it's been a disciplined patient knock for his side.
Worcs 261-7 v Sussex
Joe Leach collects three fours in the same James Coles over and Worcestershire have their first batting point.
Sussex have really let the home side get away with them in this stand, and Leach completes a 45-ball 50 with back to back boundaries to end Fynn Hudson-Prentice's next over.
His stand with Matthew Waite is now worth 101.
Notts 6-1 v Lancashire 214
Ben Duckett falls cheaply.
The England opener misses a full, straight and quick one from Tom Bailey and his middle stump is uprooted.