Leicestershire captain Colin Ackermann set a new T20 world record with bowling figures of 7-18 in their victory against Birmingham Bears.
Off-spinner Ackermann, 28, led the Foxes to a 55-run win which also boosted their quarter-final chances.
His figures surpassed the previous best of 6-5 in 22 balls by Somerset's Arul Suppiah against Glamorgan in 2011.
Meanwhile, there were also wins on Wednesday for Somerset, Gloucestershire and Northamptonshire.
But the night well and truly belonged to Leicestershire's Ackermann, whose previous best figures in the format were 3-21.
He took six of his seven wickets in two overs as Birmingham lost their last eight wickets for just 20 runs to be bowled out for 134, chasing 190 at Grace Road.
"It's quite hard to believe, I didn't know that the record was seven wickets," Ackermann told BBC Radio Leicester.
"It hasn't really sunk in yet and I think it's the first time it's turned here at Grace Road in 20 years, which is fantastic for the spinners.
"It was a great all-round performance from the team to set the game up for the bowlers."
Earlier, half-centuries from Harry Swindells (63 off 50 balls) and Lewis Hill (58 off 28) helped Leicestershire post 189-6.
Birmingham's reply looked threatening when Adam Hose (34) and Sam Hain (61) added 91 for the third wicket. But when Hose fell to seamer Will Davis at 114-3, 28 balls later the game was all over.
Victory for Leicestershire lifted them to fourth in the North Group and above Birmingham who sit a point behind and with a game in hand in sixth.
In the South Group, Kent Spitfires have caught the eye so far this campaign with some all-round performances.
But they fell to their second defeat in eight games and missed the chance to open up a lead on neighbours Sussex as Gloucestershire restricted them to just 125-8 at Bristol.
David Payne was among the Gloucestershire bowlers providing the fireworks against Kent
Kent captain Daniel Bell-Drummond did his best to try and anchor the innings with 62 from 56 balls, but the hosts put on a fine bowling display with two wickets apiece for seamers David Payne, Andrew and Chris Liddle.
There was the hint of a wobble in Gloucestershire's reply at 96-5, but Benny Howell's 25 not out off just 14 balls got them home with a six and seven balls to spare on 131-5.
Kent stay second and level on points with Sussex, having played a game more. Gloucestershire sit outside the quarter-final places on net run-rate to Hampshire in fifth.
Staying in the South Group, there was a crushing victory by 114 runs for Somerset at Essex.
Chelmsford has become synonymous with big T20 Blast totals due to its short boundaries, but normally it is the home side that inflict the damage on the bowlers.
Not this time, as Somerset posted an imposing 224-6 thanks to Babar Azam's 56 off 39 balls as well as Tom Abell's 45 from 25 and Eddie Byrom's 44 off 22 balls.
Some lusty hitting by Craig Overton in the closing overs left Essex seamer Aaron Beard with the eye-watering figures of 0-55 off his three overs.
Somerset spinner Roelof van der Merwe helped inflict a heavy defeat on Essex
Essex showed a brief threat in reply as Cameron Delport and Tom Westley set off at 10-an-over, but the Eagles sunk from 75-2 to 111 all out in the space of 30 balls.
Roelof van der Merwe proved chief destroyer with 5-32 to secure a third win in seven games for Somerset, which leaves Essex in strife with just two wins from the same number of games.
Finally, two sides struggling for consistency met at Northampton with two-time winners Northamptonshire Steelbacks hoping home advantage would work in their favour once again.
So it proved as the hosts battled to 145-6 thanks to Alex Wakeley's 47 not out and 37 from South Africa all-rounder Dwaine Pretorious.
Durham could never get going in reply as they stuttered to 32-3 inside the powerplay.
Australia wicketkeeper-batsman Peter Handscomb (63 not out) battled hard, but could not find a willing partner as some miserly bowling squeezed the runs.
Rob Keogh (3-30) took the scalps, but Josh Cobb built the pressure with just 12 runs off his four wicketless overs to ensure Durham fell 21 runs short on 124-8.
It's the London Derby on Thursday and this time Lord's is the venue as Middlesex host Surrey in the evening's only fixture.
AB de Villiers is expected to feature again for Middlesex as well as England's World Cup-winning captain Eoin Morgan.
Surrey's squad, meanwhile, features brothers Sam and Tom Curran, England batsman Ollie Pope, Australia one-day captain Aaron Finch and South Africa leg-spinner Imran Tahir.