Sam Curran takes 5-26 as Surrey beat Somerset to leapfrog them at top of South Group
Birmingham Bears go top of North Group with 21-run win at Worcestershire
Lyth (90 not out) & Malan (79) ease Yorkshire to eight-wicket win over Leicestershire
Croft hits 101 to set up Lancashire win by 35 runs at Northants
Champions Hampshire slip to narrow six-run loss at Sussex in last-over thriller
Essex recover from 1-2 to chase 176 to win and beat Glamorgan by four wickets
Haider hits last ball for four as Derbyshire earn tie at Durham
Kent beat Middlesex by 13 runs despite 121 not out by Holden
Birmingham Bears 51-1 (5.3 overs) v Worcestershire
The Bears 50 comes up but then it is the first breakthrough for the home side as Al Davies is taken at point by his former Bears team-mate Adam Hose off Pat Brown for 28.
New man in Chris Benjamin.
Birmingham Bears 47-0 (5 overs) v Worcestershire
First over without a boundary. But it it still the Bears on top here.
Brown to send down the final over of the powerplay.
Birmingham Bears 39-0 (4 overs) v Worcestershire
Tidy first over from Pat Brown until Al Davies takes a boundary off the last ball.
Birmingham Bears 33-0 (3 overs) v Worcestershire
10 more off the third over from Mitch Santner.
Good start this for the Bears, as England T20 international Pat Brown comes on.
Both openers already into double figures.
No sign so far of either Moeen or Sam Hain being missed.
Birmingham Bears 23-0 (2 overs) v Worcestershire
Both New Road scoreboards now working. Clearly welcome news for the aged BBC commentary team of Frank Watson, Chris Williams and Brian Halford.
An edged six into the top tier of the stand for Rob Yates is the highlight of the second over from Dillon Pennington, which went for 13.
Birmingham Bears 10-0 (1 over) v Worcestershire
Matthew Waite comes in for his first start for the hosts - and bowls the first over.
Rob Yates already looks in good touch, alongside Al Davies.
10 off the first over. We think. The notorious New Road scoreboard isn't properly working yet. Again!
Worcestershire v Birmingham Bears
Bad news for the Bears at Worcester tonight.
Sam Hain is out injured with a hamstring problem.
He is one of three changes for the visitors.
Jake Lintott and Jacob Bethell come in for a Bears side missing England Bazballer Moeen Ali.
Worcestershire have Matthew Waite in for the injured Kiwi Michael Bracewell, who will play no further part this season. And his T20 overseas replacement Usama Mir also plays.
We have uninterrupted ball by ball coverage of all eight games for you this evening, thanks to our BBC local radio commentators. Choose a game from the audio promos at the top of this page and we'll keep you on top of events elsewhere with regular text updates.
Image source, PA MediaSean Abbott acknowledges the crowd after scoring 110 not out against Kent at The Oval on 26 May in a score of 223-5
The meeting of the top two is the highlight of the action in the South Group this evening as Somerset welcome Surrey to Taunton.
In the last seven days, Surrey smashed 258-6 as they smashed Sussex at Hove in the Blast before chasing down a mammoth 501 to beat Kent in the County Championship on Wednesday.
That score of 258 followed previous T20 efforts of 236, 223 and 199 in their eight matches so far.
Now their batters will look to maintain that blitz against Somerset and their attack of Craig Overton, Matt Henry and Peter Siddle.
Defending champions Hampshire Hawks, currently third in the group, lost at Canterbury in their last Blast game, but will hope to get back to winning ways as they travel along the south coast to Hove to play Sussex.
The Sharks have only won two of their eight games and probably have to win all of their remaining fixtures to make the knockout stages.
Essex hold the fourth and final qualifying spot, but they could be joined on 10 points by Glamorgan if the Welsh county win their encounter at Chelmsford.
Meanwhile at Lord's, bottom side Middlesex will hope to end their wretched T20 run of 12 straight defeats against a Kent team, for whom victory over Hampshire seven days ago ended their own five-match losing streak.
It's a case of 'while the top cat's away' in the North Group tonight.
Leaders Notts don't play and in-form Yorkshire and third-placed Birmingham Bears, both have a chance to top the group and leapfrog over Notts if they win.
And the other 'mice' also have a chance of tiptoeing their way closer to the top.
The Bears have the first chance to go top in the early evening non-floodlit derby against Worcestershire at New Road - an odd choice of fixture date, which must have stumped more than a few local cricket fans, on a day when the England-Australia series is only just under way up the M5 at Edgbaston.
Image source, Rex FeaturesUsama Mir is back in the Worcestershire team in time for the two back-to-back derbies with the Bears, this Friday at New Road, then next Friday night at Edgbaston
After winning their first four matches, the hosts have lost their last three - but they have Pakistan leggie Usama Mir back tonight in place of injured Kiwi all-rounder Michael Bracewell. And they also have the psychological boost of a good home T20 record against the Bears, who have not won at Worcester since 2017.
The second side with a chance to go top tonight are Yorkshire, who have won their last five games on the spot - and will fancy themselves against bottom side Leicestershire.
But fourth-placed Worcestershire, as well as fifth-placed Durham and sixth-placed Lancashire, all have a chance to get back within two points of top spot, as the already tight North Group gets set to tighten further.
Durham host Derbyshire, while Lancs go to Wantage Road to face Northamptonshire.
Yorkshire Vikings v Leicestershire Foxes (starts 18:30 BST)
Image source, RexLooks like former umpire Dickie Bird is back in familiar surroundings at Headingley for Yorkshire's game against Leicestershire. He stopped by the nets earlier for a word with Foxes coach Paul Nixon.
Dickie, now 90 years young, played for both teams. Wonder which one he'll be rooting for tonight? (No - 'rooting' isn't a feeble joke to mark the start of the Ashes series)
Hope he has a great evening.
Image source, Rex FeaturesMost runs
Most wickets
Image source, BBC Sport
Image source, BBC Sport18:30 start unless stated
Worcester: Worcestershire Rapids v Birmingham Bears (17:30)
Lord's: Middlesex v Kent Spitfires (18:15)
Riverside: Durham v Derbyshire Falcons
Northampton: Northamptonshire Steelbacks v Lancashire Lightning
Headingley: Yorkshire Vikings v Leicestershire Foxes
Taunton: Somerset v Surrey
Chelmsford: Essex v Glamorgan (19:00)
Hove: Sussex Sharks v Hampshire Hawks (19:00)
Image source, Rex FeaturesThe players are refreshed following a seven-day break - or maybe not so refreshed if they played in the last round of Championship games which ended on Wednesday - and the T20 Blast is back.
Tonight's fixtures start an eight-day run of uninterrupted T20 action which should help decide which eight teams will make it through to the knockout stage of the competition.
Welcome to our coverage. Tonight's first match, the Worcestershire v Birmingham Bears derby, starts at 17:30, with seven to follow later.