Sam Curran smashed a maiden T20 century and career-best unbeaten 102 to help Surrey secure a home quarter-final with a five-wicket Vitality Blast win over eliminated Hampshire.
Toby Albert hit 66 to propel Hampshire to 183 but it was nowhere near enough in the end.
England all-rounder Curran was in sparkling form and slogged six sixes and seven fours from 58 balls and reached three figures with the matchwinning shot, as the hosts chased down a target of 184 with five balls to spare.
Cameron Bancroft hit his knock of 87 from 54 balls as Gloucestershire saw off Middlesex to keep their chances of reaching the knockouts alive.
The Australian shared an opening partnership of 65 from 42 with partner Miles Hammond to set a platform for the visitors and their opponents were set 180 to take victory.
Captain Leus du Plooy hit an unbeaten 73 from 52 but Middlesex lost six wickets for 39 and fell 11 runs short of their target.
Ben Green took four wickets as holders Somerset moved above Sussex with a six-wicket victory at Taunton.
Sussex never got firing with the bat and could only post 158-9 after being put into bat, Harrison Ward was the shining light with his quickfire 39 but Green finished with 4-17 from his three overs to restrict Sussex.
Somerset romped to the total with ease and clocked up 162 runs with more than three overs to spare. George Thomas blasted 42, including seven fours, while Tom Abell was 47 not out. The result means Somerset qualify for the quarter-finals and are favourites to secure a home tie with one group game left to play.
In the North Group, Saif Zaib helped Northamptonshire secure their first quarter-final spot in four years with an 11-run victory over already-qualified Birmingham.
Zaib produced 86 off just 41 balls with eight fours and six sixes alongside a 72 partnership with former England international Ravi Bopara (19) to help Northamptonshire post 197-6.
In reply, Steelbacks skipper David Willey made a blistering start with ball in hand and took two wickets in the opening over, including Moeen Ali first ball, as the Bears were immediately on the back foot on 11-3.
Sam Hain breathed life into the encounter and struck 93 off just 60 balls to take the match into the final over but they ultimately fell short.
Derbyshire earned a last-ball five-wicket success over Worcestershire to keep their hopes of reaching the knockout stages alive.
Ed Pollock top-scored for the hosts with 67 but Pat Brown picked up two wickets in the final over as he finished with figures of 4-23 as Worcestershire were restricted to 169-8.
Derbyshire were steady in reply but it was Ross Whiteley who smashed an unbeaten 41 to put them in contention to win the match and Alex Thomson was the one to get the decisive run and with it the victory.