Birmingham's fightback stumbles again as Dan Mousley is caught off the bowling of Jordan Thompson for 22.

West Indian Carlos Brathwaite is the new man in, making his T20 Blast debut.

Ethan Bamber starts off with a dot ball but then Jason Roy gets the first run of the game by cutting the second delivery to deep square leg.

Then there's some signs of nerves as he bowls a wide down the leg side.

The next one goes down leg slightly and Will Jacks flicks it down to long leg for four.

Jacks then makes it back-to-back boundaries with a drive towards long on, beating the fielder in the circle.

Jacks edges the final ball of the over, and it races all the way to the boundary. There was no slip in.

A strong start for the visitors. The outfield is fast.

Glamorgan get under way with Nick Selman and David Lloyd opening the batting.

A big chase needed.

Almost ready to go at Lord's.

Fast bowler Ethan Bamber is opening the bowling for the hosts.

The right-armer is making his T20 Blast debut and doesn't have a name or number on the back of his shirt yet.

England international Jason Roy is opening the batting for Surrey, alongside Will Jacks.

Jos Buttler-watch. The England man looks in good touch for Lancashire with two fours to move on to 12 from eight.

Good start from the hosts who have already reached 50 from just five overs.

Image source, Rex Features

Two sixes in the final over from Graeme van Buuren takes Gloucestershire to a very respectful 179-6.

Glenn Phillips was the standout with his 44, but this total is a real team effort. Seven Gloucestershire batsman reached double figures.

Another Birmingham wicket falls in the powerplay.

Matthew Waite has his second as Adam Hose is caught for 22 off 12 balls.

Yorkshire's decision to bowl first looks like a masterstroke.

Meanwhile, Marnus Labuschagne has his second catch off the bowling of Dan Douthwaite as Benny Howell falls for a solid 30.

Good response from Glamorgan, Howell was really starting to accelerate.

Just eight balls remain of Gloucestershire's innings.

No run.

England's Buttler survives.

Jos Buttler will face the hat-trick ball...

Griffiths is on a hat-trick!

Alex Davies goes for a duck.

Ah. Gavin Griffiths gets the key man Livingstone who feathers one behind to the keeper.

25 runs off 12 balls from Livingstone. I imagine Lancashire will slow down a little now. Just 3.1 overs gone.

What a start from Lancashire they're already into the 30s.

Liam Livingstone is setting down a marker. He's on 25 from 11 deliveries.

Fellow opener Finn Allen is happy to give him the strike. He's on six from six.

Image source, Rex Features

Middlesex have won the toss at Lord's, and skipper Eoin Morgan has decided to have a bowl.

Surrey counterpart Gareth Batty says he would have taken the same decision, with conditions clammy and close in north London.

Middlesex hand Blast debuts to Australian all-rounder Chris Green and right-arm paceman Ethan Bamber.

Surrey include Jason Roy and both Curran brothers, who are back early from the curtailed Indian Premier League.

Image source, Rex Features

Middlesex and Surrey begin their T20 Blast campaigns with a London derby at Lord's.

The hosts will want to put their poor County Championship form behind them, having lost six of their eight games in Group Two thus far.

Having been eliminated from the Blast at the group stage last year, Middlesex are boosted by having England limited-overs captain Eoin Morgan available for their first five group games.

Surrey finished as runners-up last season, losing by six wickets in the final against Nottinghamshire Outlaws.

Around 6,000 fans will be socially distanced at the Home of Cricket for this one.

One brings two.

Will Rhodes goes for a duck, caught off the bowling of Matthew Waite.

Birmingham Bears are in a pickle inside the first two overs.

And it looks to be a good call from Yorkshire skipper David Willey to bowl first.

He takes the ball and has Ed Pollock caught by Lockie Ferguson at deep square-leg in the first over.

Super start.

You just can't keep Labuschagne out of the action.

He catches Gloucestershire skipper Jack Taylor off the bowling of Dan Douthwaite for 25.

In comes Benny Howell at number seven. End of the 15th.

Two more games get going.

Lancashire will be batting first against Leicestershire.

Yorkshire have chosen to field first against Birmingham.