Sydney Sixers 6 for 163 (Gardner 53) beat Sydney Thunder 7 for 148 (Haynes 37, Cheatle 3-21, Gardner 3-22)
Gardner hit a vital 53 off 37 balls to rescue the Sixers from 2 for 7 after they elected to bat first. Suzie Bates and Ellyse Perry fell in Sam Bates' opening over and Sixers were again wobble on 5 for 94 when Gardner's innings ended in the 14th over.
However, Sixers' batting depth came to the fore as Nicole Bolton (28) and Maitlan Brown (29 not out) added 56 for the sixth wicket
Captain Rachael Haynes and No. 5 Chloe Tryon (32) attempted to push Thunder towards an unlikely win, but it was all Gardner. The 25-year-old opened the bowling to finish with figures of 3 for 25 to be the clear player of the match. She also claimed a terrific catch running in off the boundary to remove Sammy-Jo Johnson.
This game had originally been scheduled for Blacktown Oval before being moved due to concerns over the pitch, facilities and crowd.
Sixers will battle Scorchers in Perth on Saturday in a blockbuster top-of-the-table clash.