Utility player Damien Delaney won't be rushed back either. In the last two months, he's played just 45 minutes of reserve team football.
Both Ricketts and Delaney could be involved in Tuesday's home game with Luton.
Sam Collins and David Livermore are still missing.
Parkinson's opted to stick with Jon Parkin and Michael Bridges up front, with Nicky Forster on the bench. Nick Barmby is still absent.
Starting line-up (4-4-2): Boaz Myhill; Alton Thelwell, Danny Mills, Michael Turner, Andy Dawson; Craig Fagan, Ian Ashbee, Dean Marney, Mark Yeates; Jon Parkin, Michael Bridges.
Subs: Matt Duke, Danny Coles, Ryan France, John Welsh, Nicky Forster.