Horspath put their defence of the Hartwell Trophy on the line against Banbury in the semi-final at White Post Road on Tuesday, August 5 (6pm).
Aston Rowant are at home to Shipton-under-Wychwood in the other semi-final.
The two winners will meet at Oxfordshire T20 Finals Day on Saturday, September 20 at a venue to be confirmed.
Horspath booked their last-four post by topping Pool 1 with four wins out of four, doing the double over Oxford and Oxenford.
The reigning champions opened up with a 71-run victory at home to Oxenford with Derval Green smashing 51 off 33 balls.
Tyron Eyles (35) top-scored and Josh Richardson took 3-22 as Horspath made it two wins out of two by beating Oxford by 23 runs at the Oxford University Press Sports Ground.
A hat-trick of wins was completed with a four-wicket triumph over Oxenford at Oriel College Sports Ground with Sravan Konidena claiming 4-17 and Eyles hammering 49 from 32 deliveries.
Horspath clinched top spot with a four-wicket win over Oxford at the Recreation Ground.
Captain Amin Rafiq (3-21) pegged the visitors back, before Rayaan Dogar steered the holders towards victory with 39 off 30 balls.
Banbury, meanwhile, topped Pool 3 on run rate after finishing level on points with Bicester & North Oxford.
The Home Counties Premier Cricket League Division 1 side won four of their six games, were given a walkover and suffered one defeat.
Dave Eaton took 5-16 and Ali Short blasted an unbeaten 70 off 37 balls as they opened up with a nine-wicket home win over Brackley.
A 51-run home win against Bicester followed with Charlie Hill making 58 from 50 balls and Ben Miller hitting an unbeaten 56 from 45 deliveries.
Cropredy were then swept aside by nine wickets at the Riverside with Kieran Coyne cracking 41 from 25 deliveries.
Banbury made it four straight wins with a 74-run victory at Brackley with Richard Simpson hitting 63 off 42 balls and Coyne taking 4-6.
Cropredy conceded the return fixture, before Banbury lost by 12 runs at Bicester, but still progressed with a superior run rate.
Banbury have since emphasized their pedigree for the shorter format by being crowned Home Counties T20 champions, beating High Wycombe and Slough on Finals Day at Great Brickhill.
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