Aaron Finch smashed 51 off 26 balls and Jade Dernbach took three wickets to help Surrey to a 15-run win over Somerset in the NatWest T20 Blast at The Oval.
Somerset did well to peg Surrey back to a score of 154-8 - Josh Davey taking 3-20 - with the hosts managing only two boundaries from the final 13 overs.
Sri Lankan great Mahela Jayawardene got Somerset off to a brilliant start, striking 36 from 21 balls, but the visitors lost their way during their run-chase after spinners Gareth Batty (1-20) and Zafar Ansari (1-20) put a mid-innings stranglehold on them.
Somerset needed 33 from the final four overs with five wickets remaining, but Dernbach (3-32) conceded only eight from his final two, helping the hosts to a win that keeps their playoff hopes alive.
Jos Buttler overcame a painful blow to his left hand to smash a 20-ball half century as holders Lancashire chased down 199 to beat Worcestershire by seven wickets at New Road.
Buttler struck seven fours and four sixes in his 57, while Karl Brown blasted an unbeaten 62 off 40 balls to see the visitors triumph with 11 balls to spare.
Ravi Bopara held his nerve in the final over - conceding only four runs and taking a wicket - to see Essex earn a three-run win over Hampshire at The Ageas Bowl.
Bopara (1-26) took the key wicket of Lewis McManus (17) who had just smashed 12 runs from the final three balls of Graham Napier's penultimate over.
England's James Vince had earlier smacked 62 from 51 balls to see Hampshire off to a strong start in their pursuit of Essex's 154-run target, but the visitors held on for the win.
At Headingley, North Group strugglers Yorkshire snatched victory from the jaws of defeat after a dramatic Birmingham collapse left the hosts victors by two runs.
Second-placed Birmingham looked to be cruising to their target of 157 when they were left needing 16 runs off the final 13 balls with six wickets in hand.
However, they lost three players to run outs, two to the bowling of Tim Bresnan (2-31) and another to David Willey (2-28) to be bowled out for 154.
Gloucestershire - unbeaten in six T20 matches - suffered a shock defeat to Kent, losing by three runs in Bristol.
Joe Denly hit four sixes in a 35-ball 51 to help Kent off to flying start when batting first, but after his wicket in the 12th over, the visitors added only 50 runs from the final eight overs losing five further wickets.
In pursuit of 149, Gloucestershire too got off to a great start, with captain Michael Klinger cracking 42 off 31 balls, but they too lost their way in the second half of their innings and came up short when needing 16 from the final over.
Northamptonshire suffered only their second defeat of the season after going down to an Imran Tahir-inspired Nottinghamshire by six wickets.
Tahir took 3-13 on his T20 debut for Notts to help skittle Northants for 122, while Dan Christian's rapid 56 not out off 32 balls helped the visitors knock off the required runs with three overs to spare.
At the other end of the North Group standings, rock-bottom Leicestershire claimed a rare win, and in emphatic fashion, as they thrashed Derbyshire by nine wickets at Grace Road.
Three wickets apiece for Ben Raine (3-43) and Clint McKay (3-20) helped dismiss Derbyshire for 158 and then Leicestershire skipper Mark Pettini (71no) and Mark Cosgrove (52) both struck fifties to see the hosts home with 25 balls to spare.
South Group high-flyers Glamorgan were similarly clinical in seeing off Middlesex at Richmond, winning by nine wickets.
Eoin Morgan (58) and Ryan Higgins (57no) provided the bulk of Middlesex's 144-8, but Glamorgan made light work of the chase, Mark Wallace leading the charge with an unbeaten 69.