Greig looked to have the title in the bag after a morning 78 which was five shots clear of Wanaka's Liz McRae.
But Greig (St Clair) struck difficulties in the afternoon, ballooning out to an 86, to bring McRae (Wanaka) and Hicks-Beach (Queenstown) back into contention.
Hicks-Beach took the title in a playoff, which should give her confidence going into the contest between Otago and Southland for the Salisbury Cup at St Clair on Sunday.
Claire Patterson (Taieri Lakes) took the honours in the bronze championship by a single stroke from Heriot's Lesley Claque, while Janet Cochrane (Wanaka) triumphed in the bronze runner-up division.
The premier club was decided under the gross stableford format and Chisholm Park Weekend prospered, with 93 points.
Sally Shaw led the way with 38 points, supported by Leeanne Henry (28) and Marg Hore (27).
Led by McRae, Wanaka finished second with 92 points, St Clair on 91 and Otago was one further shot back, with 90 stablefords.
