Rush said, "We understand the Ospreys are threatening to bring a large number of fans so as the home team we will require the full backing from our loyal supporters.
"When the crowd gets behind us at the Arms Park it gives the boys a huge boost and the full advantage of being at home. We certainly had their full support against Wasps and I expect the Welsh derbies over Christmas to be no different."
The Blues completed a double over the Ospreys last season but will be looking to avenge the narrow defeat at Liberty Stadium in September when the Swansea based side visit the capital this weekend.
To avoid disappointment supporters are advised to purchase their tickets as early as possible as a sell out is likely. Tickets can be purchased by calling 029 2030 2030 or buy online with no booking fee at . Tickets will be available for collection on the day.
Alternatively limited short term parking is available at the Arms Park until Friday if you wish to visit the Ticket office to buy your tickets in person.