Cunningham had to withdraw from the Ireland squad that played Norway in Dublin on Wednesday night with the injury which has been troubling him for the last month.
Blues boss Steve Bruce could therefore rest Cunningham and bring in Purse for his first game since December 15th when he was sent-of during the 1-0 victory over Fulham at Loftus Road and picked up an ankle injury.
Purse has been back in the squad for the last four games but has been unable to regain his place because of the tremendous form of both Cunningham and Matthew Upson.
"Cunningham is extremely doubtful because he has played the last three games and hasn't trained a day in between."
