Chester booked a final group shoot out with Neston after their second consecutive victory in the Joseph Holt Trophy group stages.
And with Neston also having won both games, the group winner will be decided at Parkgate in a fortnight.
Chester batted first and got off to a disastrous start as they lost Ollie Law to the first ball. But the side recovered well on a gloomy evening, their 157-6 built around a solid 78 not out from Rick Moore.
Lee Dixon added 22 and Warren Goodwin 16.
Matt Ingram threatened briefly for Upton with a43 but Jack Williams (3-17), Will Owen (2-17) and Ash Davis (2-21), restricted the reply to 101-9.