Kent Spitfires’ winning start was ended by Sussex Sharks, while holders Worcestershire Rapids easily chased down 178 at Headingley on a packed night of action in the T20 Blast.
After five straight victories, Kent could only muster 154-8 at Hove and the hosts knocked off the runs in 16 overs to win by nine wickets.
Yorkshire Vikings made 177-7, but Rapids opener Riki Wessels smashed 91 off 51 deliveries to help his side to 179-5 and victory with 15 balls to spare.
Elsewhere in the North Group, leaders Lancashire beat Durham in a low-scoring game, Notts Outlaws thumped Birmingham Bears and Derbyshire saw off Northants.
The pick of the games in the South Group was at Taunton where Somerset smashed their way to a target of 204 set by Surrey.
The visitors made 203-4 thanks to half-centuries from opener Aaron Finch (72) and England all-rounder Sam Curran (53) who was promoted to bat at three.
But Tom Banton’s explosive 37-ball 71 set Somerset on their way and fellow youngster Ed Byrom finished the game with an 18-ball half-century on debut.
The other two matches saw Essex defend 206 to overcome Gloucestershire and winless Glamorgan fail to chase 129 to beat Hampshire at the Ageas Bowl as they were skittled for 87.
Somerset youngsters shine
A display of incredible hitting from 20-year-old Banton and 22-year-old Byrom made light work of an imposing total set by Surrey.
In just the third over, Banton sent an audacious reverse-sweep for six off seamer Sam Curran and went on to plunder 11 fours and two sixes.
Five of those boundaries came in one Tom Curran over which saw the England paceman taken for 22.
Once veteran spinner Gareth Batty removed Banton, the competition’s leading scorer Babar Azam (43), James Hildreth (31 not out) and big-hitting Byrom continued to smash the ball to all parts.
In a damaging night for Surrey’s bowlers, the Curran brothers went for 78 in a combined 6.4 overs and Jordan Clark conceded 41 from his three.
A fourth defeat in six games leaves Surrey eighth in the South Group, while Somerset are a place and point above them.
Archer quiet in Sussex win
Sussex were boosted by the return of Jofra Archer after he was released from England’s squad for the first Test against Australia.
But the 24-year-old paceman went under the radar in his side’s comfortable victory.
The World Cup winner conceded 20 in his first couple of overs before returning to pick up a wicket and finish with 1-28. Tymal Mills outshone his fellow fast bowler, taking 3-23.
It was Sussex’s batsmen who then stole the show with Phil Salt (63 not out) and Laurie Evans (65 not out) sharing a second-wicket stand of 115 to see the Sharks home easily.
Kent remain top of the South Group, but Sussex have closed the gap to just two points and have a game in hand.
Wins for North Group pacesetters
The top three – Lancashire Lightning, Worcestershire Rapids and Notts Outlaws – all had relatively comfortable evenings as they approach the halfway stage of the group phase.
Liam Livingstone starred with bat and ball in the Red Rose county’s five-wicket win – taking 2-21 as Durham were bowled out for 139 and then blasting 70 in the chase.
Worcestershire picked up a third victory in a row after fighting back superbly against Yorkshire.
Adam Lyth (68) and former Pears batsman Tom Kohler-Cadmore got the Vikings off to a flying start as they raced to 104-0 in the 12th over.
But once the pair were dismissed by George Rhodes in consecutive overs, the rest of the innings faltered.
Wessels, who pummelled 74 off 29 balls on Sunday, was at his destructive best once again hitting 10 fours and five maximums before falling nine short of a deserved century.
However, the 33-year-old had already set the Rapids well on their way to victory.
At Trent Bridge, Joe Clarke (50) and Tom Moores (69) starred for Notts as they piled up 184-4 before Birmingham Bears were dismissed for 113 in the 18th over.
The Outlaws are back in action at Lancashire Lightning (19:00 BST) in Saturday’s only T20 Blast fixture.