Alex Lees continued his superb form to help Durham book a home knockout sdtage place in the Royal London Cup with victory over Worcestershire while Surrey's Tim David hit a 55-ball century to keep alive their knock-out hopes.
Victory by 46 runs for visiting Durham at New Road ensured they are guaranteed a top-two finish in Group Two.
It is more up for grabs in Group One where Surrey's emphatic seven-wicket win over Warwickshire moved them up to third while there were triumphs elsewhere for Essex, Nottinghamshire and Leicestershire.
Durham's opening batsman Lees had struck 126 not out on Sunday to beat Essex and followed that score up at New Road with a fourth consecutive innings of fifty or more.
He was unable to reach three figures again though, bowled for 93 by Adam Finch who claimed two scalps but six maximums in David Bedingham's total of 66 from 41 balls helped the away side post 289 for nine.
Early wickets for Paul van Meekeren (three for 45) and Liam Trevaskis (three for 38) put Worcestershire on the back foot and although Jake Libby hit 76, the hosts were dismissed for 243 in the 46th over.
Durham remain top of Group Two and Essex are second after a 97-run victory over Sussex helped them qualify for the knock-out phase of the 50-over competition with one group fixture left.
Academy graduates Josh Rymell and Feroze Khushi hit 78 and 77 respectively while 53 down the order from wicketkeeper Adam Wheater saw Essex end on 321 for eight in Chelmsford.
Jack Plom, another to progress through the age groups, made early inroads on his way to three to 52 before stalwart Ryan ten Doeschate picked up four scalps to bowl out the visitors for 224. Victory for Tom Westley's side away to Lancashire on Thursday will earn a home semi-final.
Over in Group One, fireworks from Singapore international David keep Surrey in with a shout of a knock-out berth after they jumped up from sixth to third with a win over Warwickshire, who are now unlikely to finish in the top three.
The early damage at the Kia Oval came from the hosts' bowlers with Conor McKerr claiming a four-for while the leg-spin of Cameron Steel had the visitors in trouble as he finished with four for 39.
A total of 268 for nine, thanks to Craig Miles' unbeaten 31 at number 10, was never likely to be enough and so it proved. A rare single helped David bring up his century in 55 balls and he finished on 140 not out after smashing 11 sixes in his 70-ball knock to earn a seven-wicket success.
If Surrey beat Derbyshire on Thursday they will leapfrog Nottinghamshire and be through to the knock-out stages with the Trent Bridge side now sweating on their hopes of progressing further in the tournament.
Peter Trego captained Notts to a two-wicket win over Northamptonshire to conclude his team's group stage campaign on eight points, which leaves them in second ahead of Thursday's final fixtures before the knock-outs.
A five-wicket haul by Liam Patterson-White saw Northants bowled out for 210 and Ben Compton, the grandson of England great Denis Compton, helped the hosts get over the line with two balls to spare with an innings of 71.
Somerset and Leicestershire produced an entertaining affair in Taunton, but it was the away side who won by four wickets after they chased down 327.
Captain Lewis Hill led from the front with 107 and was well supported by Louis Kimber who struck 85 to help Leicestershire triumph in the 45th over to place them sixth in the table but still in with a shout of finishing in the top three.
Somerset, who dropped from third to fifth, were unable to build on George Barlett's maiden List A century in their total of 326 for seven and it leaves everything to play for ahead of Thursday's final day of group matches.
