The T20 Blast returned with a bang as 2018 winners Worcestershire Rapids stunned holders Notts Outlaws by somehow forcing a last-ball tie.
Essex, winners in 2019, were too good for Somerset at Taunton as they chased down the hosts' 185-7, while Kent's 176-6 was too much for Hampshire.
Lancashire had launched the 2021 Blast by beating Derbyshire thanks to Liam Livingstone's unbeaten 94 off 58 balls.
But highlight of the evening was the drama at Worcester as Notts buckled.
"It feels like a win," said home skipper Moeen Ali, who took a crucial 2-15 on his first appearance for Worcestershire since captaining the Rapids to defeat in the final in September 2019. "I just wanted us to fight and we showed that."
After the hosts plummeted to 63-4 off the penultimate ball of the 10th over at New Road, they were given hope in a stand of 78 between in-form Jake Libby (52 not out) and Ross Whiteley (42) before 10 in two balls from Ed Barnard lifted them to 152-6.
That total looked inadequate when Worcestershire old boy Joe Clarke - a winner of the competition in 2018 with the Rapids and again with Notts in 2020 - and fellow twice winner Alex Hales powered to 76-0 in just 35 balls, halfway to matching the home total.
But Hales got himself out for 31 going for one attempted six too many, caught at deep mid-off by Moeen. Clarke followed for 43 an over later and wickets continued to tumble.
Old heads Peter Trego and Steve Mullaney, with a combined age of 73, seemed to have used their nous to get their side home.
Even when Josh Tongue took a fine catch to remove Mullaney, Notts still only needed five off the last over. But Trego got off strike and Tongue bowled a fine last over to keep him off it until the final ball.
First Luke Fletcher was run out and then, needing two off the last ball, 39-year-old Trego was also run out by Barnard going for the second. That meant the 31st tie in the 18-year history of the competition - and Worcestershire's first.
"We believe in ourselves," said England all-rounder Moeen. "We kept saying 'a couple of wickets, get Halesy and Clarkey out and we've got a chance'."
Livingstone had already got this year's tournament off to a great start as Lancashire finally saw off Derbyshire by six wickets in the last over at Emirates Old Trafford.
The 27-year-old England limited-over international struck two sixes and 10 fours in his unbeaten 94 off 58 balls.
Derbyshire set an imposing 168-7, fuelled by 59 from Lancashire old boy Luis Reece and Leus Du Plooy (34). But Jos Buttler (30) and New Zealander Finn Allen (29) helped Lancashire to 171-4 off 19.3 overs.
England wicketkeeper Buttler, batting at four, hit three fours in his 28-ball knock - the first of six scheduled T20 appearances for his county. But he was outshone by Livingstone's second-best score in T20 cricket.
Derbyshire wasted the best chance to remove him when Matt Critchley and du Plooy collided painfully just when it looked like Livingstone might hole out - and the catch was spilled.
That added to Derbyshire's woes, having earlier lost key man Wayne Madsen, who had to retire hurt on 12 after being struck by a throw from Lancashire captain Dane Vilas.
Kent claim first win of the season
After eight games without a win this season in County Championship cricket, Kent finally triumphed in the shortest form of the English county game.
Kent's top three, Joe Denly (44), Daniel Bell-Drummond (42) and Ollie Robinson (48) helped the Spitfires post 176-6. And the hapless Hampshire Hawks never really looked like getting there.
Only Joe Weatherley (37) and James Vince (34), in an opening stand of 51 with D'Arcy Short (29), ever looked like helping them reach their target.
Fred Klaasen took 4-32, while Darren Stevens, back in favour in T20 cricket for Kent for the first time in four years at the age of 45, claimed a very tidy 2-22.
Essex Eagles won with seven balls to spare against Somerset at Taunton.
Young paceman Jack Plom had the honour of hitting the winning run after the early shock of being smashed for 33 off his first over by converted opener James Hildreth - including successive sixes over long-on, four fours and two no-balls.
But, after 57 off their first three overs, Somerset managed only 11 from the next three.
And, although they were chasing the biggest target of the day, Essex had New Zealand international Jimmy Neesham's explosive 53 to thank for setting up their three-wicket win.
They recovered from a poor start as Neesham hammered seven fours and two sixes in his 23-ball half-century to quieten the 1,900 crowd.
Lancashire are back in action on Thursday with another home game against Leicestershire Foxes (18:30 BST), while Derbyshire's next game is on Friday, also against the Foxes, at Leicester (18:30).
Thursday's other North Group game will be Yorkshire and Birmingham Bears getting their campaign under way in Leeds (18:30 BST).
Worcestershire, who are away to Northants (19:00), and Notts, who host the Bears (18:30), do not play again until Friday.
In the South Group, Glamorgan play Gloucestershire in Cardiff on Thursday (17:30) and the London derby between Middlesex and Surrey takes place at Lord's (19:00).
Kent, Hampshire, Essex and Somerset are all next in action on Friday as part of a bumper crop of eight fixtures.