CHEPSTOW 1st XI missed out by just nine runs in an exciting run chase at high-flying Abergavenny, earning nine points to stay out of the drop zone.
Amazingly, Filip Chitnis took a hat-trick in the last three balls to end the Aber innings on 218 all out.
But he was the last man standing on 10 as the visitors' reply ended on 209 all out, two balls short of the full 50 overs.
While victory secured promotion from South Wales Premier 2 for the hosts, Chepstow face league leaders Ynystawe at home on Saturday (August 31) in their final game, while second to bottom Port Talbot host bottom side Dafen.
Ryan Avery with 58, Will Glenn 30, Dan Skipwith 23 and Joe Harris 38 helped propel Aber to 218-7 in the final over, when Chitnis suddenly weaved his magic, bowling David Clarke for nine and the last two batsmen for golden ducks.
There were also wicket braces for Jason Dobbie and Rhys Leach.
But except for Gareth Ansell, the Chepstow top order struggled, with just 31 scoring runs for the next six batters, leaving them on 110-7 when he fell for 39.
Leach and Dobbie then mounted a fightback though, with a 64-run eighth-wicket partnership before the latter went for 27 (174-8), quickly followed by Lewys Jones for one (178-9).
The visitors still weren't done though as Leach and Chitnis continued the chase, finally coming undone with the dismissal of the former for 58.
The third-placed 2nds won by 19 runs at home to Pontymister & Crosskeys 1sts in SEW4, Henry Sullivan firing 40 and Jared O'Brien 33 not out in their 196-7 before dismissing the visitors for 176, Philip Richardson with three wickets and Sullivan and Hemayatullah Seddiqi with two apiece.
SEW 12E leaders Chepstow 3rds were also 63-run winners at home to Crumlin 2nds, scoring 176-8 before skittling the visitors for 113 in 25 overs.
Josh Adams hit 53 and Raahi Kumar 38, while Huw Rogers and Ben Tate took three wickets apiece.