Sussex saw their unbeaten T20 Blast run come to an end as Surrey beat them by 26 runs at The Oval.
But the Sharks still sit a point clear at the top of the South Group with a game in hand on the chasing pack.
Surrey made 163-8 thanks to 48 from Ollie Pope and 47 from Sam Curran before restricting Sussex to 137-8.
Meanwhile holders Worcestershire Rapids pulled off a remarkable three-run win against Durham while Leicestershire demolished Derbyshire by 55 runs.
Sharks lack bite for once
Sussex Sharks have looked the all-round package in this season’s Blast so far with six wins from eight games before their visit to a sold-out Oval.
Despite chasing 164, they would have fancied their chances of beating a Surrey side who have largely failed to live up to their star billing.
But the hosts finally came to the party with both bat and ball on their own patch.
Firstly, Sam Curran made the short trip across the Thames from Lord’s in the morning after being released by the England squad to smash five fours and three sixes in his 24-ball 47.
Fellow England international Pope helped add 59 for the third wicket before late runs from Tom Curran (23) and Jordan Clark (15) pushed the score beyond 160.
Sussex looked on course at 60-1 with Luke Wright (25) and Laurie Evans (34) in the middle, but Surrey got their bowling partnerships spot on to squeeze the runs and make regular breakthroughs.
Imran Tahir’s 3-24 and Tom Curran’s 3-30 gave the Sharks too much of a mountain to climb in the closing overs as David Wiese found himself stranded on 31 not out at the end.
Surrey’s victory was just their third in 10 matches this campaign and keeps their slim hopes of a quarter-final place alive.
Rapids hold nerve in low-scoring thriller
Worcestershire have found a very helpful knack of winning games from seemingly unwinnable positions.
Their visit to Durham was the dictionary definition of nail-biter as they somehow managed to defend just 117.
Only Tom Fell (28) and Ross Whiteley (24 not out) had got to grips with a slow surface as Matty Potts took 3-22.
Durham’s reply looked to be on course for a routine win as openers D’Arcy Short (42) and Scott Steel (31) put on 79 in 12 overs.
But then came the turnaround and some miserly match-winning Worcestershire bowling.
Daryl Mitchell took 2-17 from his four overs and Alex Lees found himself suddenly having to take control as wickets fell around him.
It came down to Durham needing nine to win off the last over bowled by Rapids seamer Pat Brown.
Brown, the surprise package of Worcestershire’s Finals Day triumph last season, proved his worth once again conceding just five singles and dismissing Stuart Poynter to see his side over the line.
The win moves Worcestershire into second in the North Group while Durham dropped out of the top four with their fifth defeat in 10 games.
Foxes on fire in East Midlands derby
Durham’s place in that top four has been taken by Leicestershire, who once more showed they are not a side to be taken lightly.
Derbyshire Falcons found themselves on the receiving end this time of a fine display in the field as they were bowled out for just 94 chasing 150 on home turf.
Leicestershire had battled their way to 149-7 thanks to Mark Cosgrove’s 38 up top and Colin Ackermann’s 28 in the middle order.
Derbyshire would have most likely fancied chasing that down, but any hopes of a home win were rapidly extinguished once they slumped to 24-6 at the end of powerplay.
Fresh from his world-record 7-18 with the ball against Birmingham Bears a week ago, Ackermann was back to do more damage.
This time the South African off-spinner bagged 3-9 from his four overs while Gavin Griffifths took 3-14.
Leicestershire move a point ahead of both Derbyshire and Durham in the race for the quarter-final places, which all nine teams in the North Group will argue they still have a chance of making.
Well, in theory eight games are on the fixture list for another bumper Friday Night of action, including North Group leaders hosting Birmingham Bears at Old Trafford.
But a rather nasty-looking weather forecast may play its part in significantly disrupting play.
Fingers crossed the weather gods look kindly on cricket grounds up and down the land.