Dom Bess opts for a change of angle, bowling around the wicket and packing in a trio of close catchers on the leg side - but without any initial success.

So the off-spinner switches back to over the wicket for the last two deliveries of his over. All about trying to keep the batters guessing.

This has a feel of a one day game about it now.

Glorious sunshine, 50-50 outcome. What more could you want?

James Hayes fires down the 77th over at a cost of four runs and Worcs need a further 127.

Where is your money?

First runs of the afternoon session as Ben Foakes glides a ball from Oliver Hannon-Dalby down to third man for four. That apart, five dots.

A moment of anxiety for Essex supporters as Matt Critchley's concentration dips, he chases a wide ball from Dom Bess and it sails up in the air but drops short of the fielder at backward point.

Critchley has dug in grimly while Michael Pepper does most of the scoring in this partnership, but both remain immovable for Yorkshire at the moment.

We can expect at least another nine overs of uninterrupted spin, with a new ball available after that point.

A loose shot from Jake Libby off Fynn Hudson-Prentice flashes through between first and a very wide second slip and races down for a welcome if fortunate boundary.

His final ball sees Brett D'Oliveira go for another cut and miss as the ball sails through John Simpson. Just 131 needed now. Four overs to the new ball.

Adrian Harms
BBC Sussex

It is the best weather of the day, the clouds are relatively high and the ground is now bathed in sunshine.

There is still some wind about and the Union Jack is fluttering away.

The light is good compared to this morning's overcast skies which produced testing conditions to bat in.

Following the extended morning session at Edgbaston, we are about to resume. Surrey need another 28 runs to wipe out any possibility of being asked to follow on.

And even if they fall short, you wonder whether Alex Davies will opt to give his Warwickshire batters some practice out in the middle ahead of Friday's game against Hampshire - also at Edgbaston - rather then tire out his bowlers even more.

Fynn Hudson-Prentice reminds there is still danger in the old ball cutting Brett D'Oliveira in two (big appeal turned down) and then beating the Worcs skipper's attempted cut.

D'Oliveira walks down the pitch and dabs down a couple of offending patches before getting a sound forward defensive right out of the training manual.

A cut is rattling to the boundary but Jack Carson pulls off a nice stop at point. A dot to finish gives F H-P a maiden, the third from the bowler this innings.

Image source, Rex Features

As if being top of the table wasn't good enough news for Nottinghamshire followers, there is more reason to celebrate with England opener Ben Duckett signing a new contract to run until the end of the 2027 season.

He only played three Championship games for Notts last summer and has made just the one appearance so far this summer but it is still a signal of the club's ambition to challenge again for honours.

"I love playing at Trent Bridge, it’s my favourite English ground, and this team and coaching staff are a fantastic group that have been so valuable for my development on and off the field," the left-hander said.

100 partnership for Critchley and Pepperpublished at 14:05 British Summer Time

14:05 BST

Essex 145-4 (target 520) v Yorks

And another round of hand-clapping from the spectators for another Michael Pepper single - this one a sweep off Dom Bess that stretches his partnership with Matt Critchley into three figures.

50 for Michael Pepperpublished at 14:03 British Summer Time

14:03 BST

Essex 144-4 (target 520) v Yorks

Image source, Rex Features

Michael Pepper raises his bat after pushing Dan Moriarty for a single that takes him to his fifth first-class 50 from 155 balls.

It could certainly prove to be one of his most valuable innings for Essex if it enables them to stave off defeat today.

This partnership between Worcs skipper Brett D'Oliveira (25) and Jake Libby (123) is up to 61 and they are applying as much pressure on the fielders as possible.

They are running hard and threatening twos all the time.

James Hayes bowls an awful leg side delivery which has bounds away for four byes and now more good running as they take two to James Coles down at third man.

It's attritional at the moment, which might seem a surprising way to describe a passage of play with two spinners on.

Yorkshire keep probing in search of a breakthrough, but so far they haven't managed to find a way through Matt Critchley and Michael Pepper - or even created anything in terms of clear-cut chances.

Just one from the over from Fynn Hudson-Prentice.

There are 10 more overs before the new ball is due which has the feel of a pivotal passage in this chase.

Jake Libby and Brett D'Oliveira are moving along at just under three an over at the moment which might take them to 240-250-ish some 110 or so away from the finish line.

Will they may be tempted to go a little harder in order to knock off more before having to deal with a refreshed Ollie Robinson?

Intriguing moment in the contest.

In terms of run scoring, not a great deal is going on - much as it was at the start of the morning session - but Yorkshire are continuing to rattle through the overs quickly.

With Adam Lyth continuing after lunch alongside Dom Bess, the visitors have already bowled 36 of their mandatory 96 for the day.

Remember, though - that figure of 96 is a minimum rather than a maximum, so Essex still have a long way to go before they can start visualising the prospect of a draw.

200 up for Worcspublished at 13:45 British Summer Time

13:45 BST

Sussex 284 & 256 v Worcs 180 & 201-5 (target 361)

Two runs off the third ball of the second session from James Hayes and another milestone is ticked for the chasing side.

After lunch, it's still a diet of spin for Yorkshire as Dom Bess bowls the first over of the afternoon session and gets the ball to ping up off the edge of Matt Critchley's bat, but it flies to safety.

Four byes conceded in that over and that extends the partnership between Critchley and Michael Pepper to 90.

Here we go for the penulimate session of a finely poised contest.

The numbers that matter are these: Sussex need FIVE wickets, Worcs need 162 runs.

James Hayes has the ball and Brett D'Oliveira is on strike.

Play.

Victoria Polley
BBC Essex Sports Editor

Essex are putting up a good fight so far on day four.

There haven’t been too many balls Pepper and Critchley have been able to leave but they’ve played sensibly and steadily.

The longer these two can dig in and stick around, the more hope there is for an Essex draw.