Elsewhere, the Birmingham Bears remain without loss with their openers Sam Hain (42) and Ian Bell (28) still going, but the runs haven't exactly been raining down either.

The visitors are 78-0 against the Worcestershire Rapids off just shy of 10 overs.

Meanwhile, Ben Duckett is still unbeaten on 69 for Northamptonshire Steelbacks, who are 132-4 off 16 overs versus Derbyshire Falcons.

for Aaron Finchpublished at 8 overs

8 overs

Essex v Surrey 70-3

Image source, Rex Features

I'm fascinated by Aaron Finch. How can you chew gum while smashing the ball all around the ground?

Doesn't seem to put him off; he's seeing it like a football. A full toss from Ashar Zaidi greets the mid-off boundary before a drag-down is clubbed over the legside for six.

He has 51 off 24 balls, after surviving a close-run single off the final ball.

Ravi Bopara's canny medium pace takes the seventh over.

Amid the chaos, Aaron Finch is looking good. He chops Bopara's back-of-the-hand slower ball down to wide third man for four. A single from the final ball takes him onto 39 from 19 balls.

Here's why Jason Roy wasn't a happy bunny. As you can see it's a bit of a stinker from the umpire Richard Kettleborough.

Rory Burns slashes one down to third man for four to get under way. But this is a very good start by Essex. One over of the powerplay left.

Elsewhere, Adam Lyth has passed 50 for Yorkshire, who are 120-2 after 12.1 overs against Nottinghamshire.

Meanwhile, Northamptonshire's Ben Duckett has also made a half-century, with the hosts 98-1 off 11.2 overs versus Derbyshire.

And England man Jos Buttler has hit a couple of boundaries so far to reach 19 not out, with Lancashire 94-3 off 10 overs at Durham.

Finch tees offpublished at 4 overs

4 overs

Essex v Surrey 30-1

Jamie Porter's slower ball gets the treatment over mid-wicket for four from Aaron Finch first up.

Phwoaarrr. The second ball is even better, Finch producing a lovely flow of the bat and high left elbow to propel it back over long-on for six. That's no slog - beautiful technique.

Mark Stoneman is struggling on four off eight balls, but Finch has got going.

Image source, Rex Features

Angus McPhail: Roy didn't look out real time, and confirmed on replay, not a great start from the umpire

Josh Roberts: What a shocking umpire decision to give Roy out. Impact clearly outside off stump...

Mike Crew: Let the carnage begin

Good fielding from Essex, with Simon Harmer at backward point and Ryan ten Doeschate at mid-off pulling off good stops.

Mohammad Amir ends the over with two testing deliveries into Mark Stoneman's pads. Five runs off the over. Jason Roy's wicket may have been fortunate, but this is a good start from Essex.

Jamie Porter bowls very straight, restricting room to Aaron Finch, who loves to go over the offside.

Finch takes a risk off the last ball, chipping narrowly over Ryan ten Doeschate at mid-off, with the Essex skipper's dive in vain. Eight off the over, but not convincing for the visitors so far.

Well, we got our drama first up. The replay with ball tracking shows Jason Roy was right to be upset with the decision - the ball was going on to miss the stumps.

Aaron Finch has been joined by Mark Stoneman in the middle.

Jason Roy and Aaron Finch are out in the middle. It'll be Mohammad Amir and Jamie Porter to open the bowling for Essex.

We should be in for an explosive start at a packed Chelmsford.

North Group

Durham v Lancashire - Lancashire are 69-1 off six overs after Durham won the toss and chose to field.

Northants v Derbyshire - Northants are 62-1 off 7.3 overs after Derbyshire won the toss and chose to field.

Yorkshire v Nottinghamshire - Yorkshire are 73-2 off seven overs after winning the toss and choosing to bat first.

South Group

Glamorgan v Hampshire - Hampshire are 59-3 off 6.3 overs after Glamorgan won the toss and chose to field.

Image source, Rex Features

You guys have been brilliant at getting in touch throughout the English domestic season so far.

Which team do you think could spring a few surprises in the T20 Blast? Any players you think will stand out?

Keep your Tweets coming this evening using #bbccricket

Worcestershire fought back to post 152-9 in the West Midlands derby at New Road.

Birmingham, who won the toss and elected to bowl first, reduced their rivals to 66-5, with Rikki Clarke taking 3-20 from his four overs.

But a 78-run partnership between Ben Cox (43) and Ross Whiteley (40) saw the Rapids respond before three wickets in Oliver Hannon-Dalby's final over.

Image source, Rex Features

Chelmsford has a reputation for its vociferous crowd, but Surrey and England opener Jason Roy, who was the only player to score two centuries in the competition last season, says he cherishes a lively atmosphere.

"It's a very simple game, T20, it's a case of trying to hit it for six and trying to get wickets," he told BBC Radio London.

"You always get put in your place down there [in Chelmsford]. The crowds get a little bit ahead of themselves - it's never a dull evening.

"It a big opportunity for us to go and have an away game and get off to a good start."

Image source, Getty Images

Essex come into the T20 Blast - a competition they have never won - full of confidence, sitting 29 points clear at the top of Division One of the County Championship.

The Eagles, who have reached Finals Day four times, but have been knocked out in the first semi-final on every occasion, give a T20 debut to Mohammad Amir.

Despite their star-studded line-up, tournament favourites Surrey have failed to get out of the group stage in the last two seasons.

They have overseas signing Aaron Finch in the side, but Jade Dernbach captains in the absence of Gareth Batty, who has a calf injury, while Kumar Sangakkara also misses out with a split webbing.