Nottinghamshire secured top spot in the Group B table, and a home Royal London One-Day Cup quarter-final to boot, with a one-wicket win over Warwickshire at Trent Bridge.
Alex Hales celebrated his England ODI call-up with a century but it was left to No 10 Luke Fletcher to hit the winning runs off the final delivery as Nottinghamshire chased down a target of 303.
Opening batsman Hales' 104 came off 90 deliveries but a collapse from 218-3 to 281-8 left 22 needed from the last two overs.
Recordo Gordon's penultimate over disappeared for 18 runs - including Ajmal Shahzad being caught off a no-ball and then hitting a six - and Fletcher (9no) finished the job in the company of last man Harry Gurney (1no) after Shahzad (27) was run out with three still required.
Warwickshire had earlier piled up 302-7 after choosing to bat, Jonathan Trott (108) and Tim Ambrose (98) sharing a third-wicket stand of 176, while seam bowler Fletcher finished with 4-44.
Somerset's seven-run defeat to Surrey on the Duckworth-Lewis method ensured Warwickshire ended up third in Group B and will be on the road in the quarter-finals.
Steven Davies (50) and Aneesh Kapil (59) each hit half-centuries in Surrey's total of 284-9.
Somerset skipper Marcus Trescothick led the reply with a 54-ball 80 but, on 146-4 in the 25th over, floodlight failure at The Oval meant the visitors' target was revised to 275 in 46 overs.
Seamer Tim Linley (3-68) and left-arm spinner Zafar Ansari (3-38) both claimed three wickets as Somerset were all out for 267 in 44.1 overs, Surrey's first win of the competition but not enough to prevent them finishing bottom of the group.
Kent's first defeat
Kent were already guaranteed a home semi-final but they lost their unbeaten record in the competition with a seven-wicket defeat to Middlesex at Canterbury - meaning they had to settle for second place behind Nottinghamshire in the final table.
Daniel Bell-Drummond's 51 was the top score as Kent were bowled out for 191 in 43.1 overs after being sent in on a dry, spin-friendly pitch.
Middlesex, who finish seventh of the nine Group B teams with three victories, knocked off their target with 6.1 overs to spare thanks to opener Dawid Malan's 76 not out.
The last of the four quarter-final places available from Group B went to Durham, who were not in action on the night, while Jacques Rudolph starred in Glamorgan's seven-wicket (D/L) success in the dead rubber against Sussex.
South African opener Rudolph finished unbeaten on 169 from 150 balls to see Glamorgan to a target of 329 in a match reduced to 48 overs per side by rain.
Luke Wright's 127 and 92 not out from teenager Harry Finch had earlier powered Sussex to 323-8.
The final night of Group A fixtures is on Thursday.