Acting captain Alfonso Thomas claimed two wickets in the final over as Somerset beat Gloucestershire by seven runs in a thriller at Taunton.
The home side, who left out skipper Marcus Trescothick following a poor run of T20 form, posted 175-8 after losing the toss, Nick Compton top-scoring with 46 and opening partner Craig Kieswetter contributing 39.
Benny Howell was the pick of the Gloucestershire bowlers with 2-23 from his four overs, while left-arm spinner Tom Smith picked up 2-24 from three overs.
In reply, Gloucestershire looked to be cruising on 115-1 in the 13th over, but Somerset's bowlers stuck to their task, with Dirk Nannes showing all his experience at the death before Thomas dismissed Howell and Adam Rouse to wrap up victory.
The result keeps Somerset in the hunt for a quarter-final place, while leaving their neighbours with a huge task to qualify.
Glamorgan's Jacques Rudolph hit 75 off 56 balls, including nine fours, to set up a nail-biting four-run victory over Surrey at the Oval, as the Welshmen leapfrogged their opponents to move up to third in the NatWest t20 Blast South Division.
After being put into bat on an overcast evening, Glamorgan posted 192-4 - the highest total at the Oval in domestic Twenty20 cricket for four years.
Thanks to another superb knock from Jason Roy, whose 60 came in just 41 deliveries, and Azhar Mahmood's spirited 36 not out off 16 balls, Surrey came within a whisker of pulling off an inspired victory, hitting back with 188-4.
Surrey went into the final over needing 13 to win. That was shaved to seven off three balls when Solanki came within inches of hitting a six to deep extra cover off Michael Hogan, who then held his nerve to secure victory.
Paul Stirling's belligerent 64 at the top of the Middlesex innings set the tone for a surprisingly easy 50-run victory over Hampshire at the Ageas Bowl.
Middlesex's win, achieved with 20 balls to spare, was only their second of the NatWest Twenty20 season - at the 12th attempt - but it was no fluke and not even closely contested.
The visitors mustered 173-6 after being put into bat, and Hampshire slumped from 35 for no wicket to 123 all out in the 17th over, losing all their wickets for 88 runs in dramatic fashion spread over little more than 12 overs.
Stirling struck seven fours and two sixes off Matt Coles and Danny Briggs from 41 balls, featuring in crucial stands of 52 with Dawid Malan for the first wicket in six overs and then 53 for the third with teenager Ryan Higgins, making light of the early loss of captain Eoin Morgan in between.
Hampshire bat a long way down in one-day matches and Coles gave them hope of a miracle recovery by striking Neil Dexter for two sixes in three deliveries, but the revival was only temporary.
Kent withstood a remarkable late burst of hitting from Chris Jordan, Ben Brown and Will Beer to pip Sussex by three runs in a dramatic contest at Hove.
Alex Blake's exhilarating 53 not out from 32 balls, including five sixes, had lifted Kent to 149-9 - far more than looked likely for most of their innings - and then the game looked up for Sussex as they collapsed to 43-5 after 10 overs.
But Brown, with 33 off 22 balls, Jordan, with a 26-ball 37, and Beer - whose 25 took just 12 balls - almost snatched it at the death.
Sussex had needed 47 from their last three overs, 32 from the last two, and 18 from the final over, but
the lower order trio smashed seven sixes between them - three by Beer - to leave Kent hugely relieved.
Jordan, who drove Mitch Claydon for six from the fourth ball of the 20th over, holed out to long off when eight runs were required off the last two balls.
The catch, by Ben Harmison, finally sealed a win for Kent that keeps up their hopes of quarter-final qualification from the South Division. Defeat, for Sussex, makes it almost impossible for them to qualify.