Somerset continued their perfect T20 Blast start with an 11-run win over Essex – but Worcestershire suffered a first loss against Northamptonshire.
Yorkshire overcame Derbyshire Falcons by seven wickets and Notts Outlaws saw off Lancashire Lightning.
Leicestershire Foxes recorded a first win, beating Durham by seven wickets.
Elsewhere in the South Group, Surrey completed a final-ball victory over Kent Spitfires and there were wins for Gloucestershire and Glamorgan.
Gloucestershire inflicted a sixth consecutive defeat on Middlesex, with Ollie Price producing a telling performance with bat and ball in their seven-wicket win, as Sue Redfern made history by becoming the first woman to stand as an on-field umpire in the competition.
Meanwhile, Glamorgan won at Sussex by 32 runs to register their fourth win in five games and inflict a second successive defeat on the Sharks.
Zaib inspires Steelbacks to win at Rapids
Worcestershire’s 100% record ended in a thrilling finale as Saif Zaib struck 16 in three balls to claim victory for Northants Steelbacks with two balls to spare.
Requiring 14 from the final over at at New Road, chasing down the Rapids’ 178-6, the first delivery was a dot ball before Zaib hit Pat Brown for consecutive sixes and a four to snatch the win.
Zaib finished on 70 from 35 balls in his match-winning innings, ably supported at the other end by Lewis McManus as the Steelbacks picked up a third win of the campaign.
Opener Ricardo Vasconcelos fell six short of a half-century and there was also an important contribution from Josh Cobb (23).
After being put into bat, Worcestershire lost opener Michael Bracewell cheaply but captain Brett D’Oliveira (38) and Jack Haynes (26) saw them to 61-1 in the seventh over.
Adam Hose and Kashif Ali failed to fire, both falling to Freddie Heldreich (3-28) but Mitchell Santner’s 33 from 21 gave the Rapids’ total a boost.
Ben Cox, who struck the ball cleanly with some big shots in an unbeaten 46, added 51 with Ed Pollock in the final overs but it proved to not quite be enough as the Rapids’ four-game winning streak was brought to a halt.
Notts send Lancashire to fourth straight loss
Notts Outlaws leapfrogged opponents Lancashire and moved up to third in the North Group, with their five-wicket win making it four defeats on the spin for Lightning.
Matthew Carter was in good form with the ball, dismissing opener Phil Salt and Steven Croft as Lightning fell to 41-3 just after the powerplay, with Jos Buttler bowled for 23 off 16 by an excellent Shaheen Afridi yorker.
Liam Livingstone’s 30-ball innings of 34 ended when he was caught on the boundary by Alex Hales off Calvin Harrison, with the bowler then taking out Luke Wood first ball.
Colin de Grandhomme made just three before falling to Jack Brooks, who wrapped up the innings by having Jack Blatherwick caught as Lightning were bowled out for 145 in 18.3 overs.
Joe Clarke was the main aggressor in the early overs of the Outlaws chase, with Hales taking a back seat as the pair put on 58 before Clarke skied a delivery from Blatherwick for a caught-and-bowled and departed for a 24-ball 42.
Blatherwick also accounted for Hales, for 17, and when the dangerous Colin Munro departed for only 14 off Livingstone’s bowling Lancashire sensed a chance with their opponents on 80-3.
But Matthew Montgomery and Samit Patel added a run-a-ball 19 and 14 respectively and it was the unbroken partnership of 40 between Tom Moores (26*) and Steven Mullaney (14*) that got Notts over the line with seven balls to spare.
The Outlaws are level on points with Worcestershire and Birmingham Bears above them, albeit having played more games, while Lancashire have lost their early season form when they won their opening three.
In-form Malan leads Yorkshire to win
Dawid Malan continued his fine recent form, hitting an unbeaten 81, to help Yorkshire Vikings beat Derbyshire Falcons and record their third win in a row.
The England batter has been instrumental in Yorkshire’s upturn in form and he received good support from Adam Lyth (31) and David Wiese (30) as the hosts chased down Derbyshire’s 166-8.
Both teams had come into the game with identical seasons – winless in the County Championship and having lost their first three games in the T20 Blast before winning their next two.
Derbyshire’s Wayne Madsen, another in-form batter, fell six runs short of becoming the first man in T20 history to score six successive fifties – with his 44 off 26 meaning he remains one of seven players worldwide to have scored five half-centuries in a row.
Pakistan opener Haider Ali’s belligerent 74 off 47 balls was the feature of Derbyshire’s innings as he and Madsen guided them to 147-2 in the 17th over.
But when the pair fell in quick succession the innings lost momentum as they lost a host of late wickets to finish on 166-8, with Ben Mike (3-39) impressing for the Vikings.
Foxes end wait for first victory
Bottom side Leicestershire picked up their first win of the T20 campaign as a career-best 55 from Louis Kimber helped them chase down 169 to win at Durham with two overs to spare.
Foxes openers Nick Welch (30) and Lewis Hill (25) got the run-chase off to a good start and the visitors were 92-3 in the 12th over when Luke Robinson had Rishi Patel caught for 16
The hosts could not break up the fourth-wicket Foxes partnership of Kimber and skipper Colin Ackermann, who finished unbeaten on 33.
Ackermann won the toss and decided to field and Josh Hull (3-35) had some early joy, removing Durham openers Alex Lees and Graham Clark in the space of three balls.
After Michael Jones hit 21, Ollie Robinson starred with the bat for Durham, striking an unbeaten 69 from 43 balls.
He put on 80 with Ashton Turner before Turner fell for 46, which halted their momentum as they ended on 168-6.
Somerset march on against Eagles
Somerset had won their opening five South Group games but Essex performed brilliantly in the field to dismiss the 2005 winners for 150, with debutant Sean Dickson (42) and Tom Lammonby (34) the key contributors as Daniel Sams took 4-20.
However, the hosts defended what looked an under-par score at Taunton as Matt Henry and Ben Green took three wickets each.
Henry gave Somerset hope by dismissing Adam Rossington in his first over and Robin Das in his second, with Essex 49-2 at the end of the powerplay.
Michael Pepper proved to be the dangerman for the Eagles, especially after surviving a tough chance to Henry at short third man off Lewis Gregory on 29.
By then Matthew Critchley had fallen on three to a fine running catch from Roelof van der Merwe and a fourth wicket fell when Paul Walter, on two, skied to cover in Green’s first over.
Pepper moved to an impressive fifty off 31 balls in the 11th over but lost another partner when Tom Westley was bowled by Van der Merwe and suddenly Essex required seven an over at 97-5.
The size of their task increased when Pepper was caught behind for 63 off Van der Merwe, stepping back to strike through the off side.
Simon Harmer and Sams offered late resistance but both departed in the space of three balls before a fine running catch by Henry to dismiss Ben Allison and a run-out secured a sixth consecutive win for table-topping Somerset.
Surrey hold nerve against Spitfires
There was a high-scoring thriller in Canterbury, where Kent Spitfires posted a competitive 173-5 despite Surrey spinners Will Jacks (3-28) and Sunil Narine (2-28) causing issues for the batters.
Yet top scorer Jack Leaning (34) was dropped twice as he and George Linde added 51 runs in the final five overs.
Surrey began their reply aggressively, putting on 62 without loss in the powerplay, but their momentum was checked when Jacks and Sam Curran both holed out and Linde then removed Ben Foakes and Laurie Evans (52) in the space of four balls to leave the visitors 97-4 after 12 overs.
Jamie Smith took up the challenge, supported by Sean Abbott, and hit four sixes to breathe new life in to the Surrey chase and leave nine required off the final over.
Veteran Spitfires paceman Michael Hogan managed to take it to the final ball, with the first four deliveries yielding four runs and Smith sweeping four from the penultimate ball to tie the scores.
Smith managed to cut the one run required from the final ball – although he and Surrey had a scare as Leaning almost took a spectacular one-handed diving catch at point – and ended on 49 not out off 29 balls as Surrey scraped home to record their fourth win in six outings.
Further defeats for Middlesex and Sussex
Sussex had captain Ravi Bopara and fast bowler Tymal Mills back in their side but, after winning the toss and deciding to bowl, gave away 16 extras in the powerplay and 23 overall as Glamorgan posted 219-5.
The visitors made the most of a flat pitch, a fast outfield and some wayward bowling as Chris Cooke top scored with 50 – a knock which included four fours and four sixes – and Colin Ingram contributed 48.
Sussex could not keep up with the required rate and never looked in the contest, despite a plucky innings from Tom Alsop, who scored 58 from 42 deliveries, and a contribution of 45 from Michael Burgess as the Sharks finished on 187-8.
Middlesex were put in to bat at Bristol and struggled to build meaningful partnerships as they made 139-9 in their 20 overs.
Max Holden contributed a valuable 34 and wicketkeeper Jack Davies ended unbeaten on 46 as Gloucestershire took wickets at regular intervals to keep a lid on things, with Ollie Price (2-18) the pick of the bowlers.
The 21-year-old then top scored with 46 and shared in crucial partnerships of 60 with Miles Hammond and 52 with Zafar Gohar (37 not out) as Gloucestershire chased down a target of 140 with 10 balls to spare to register their second win in three days.