PNE defender Cunningham has surgery
Cunningham, who had been PNE's stand-in skipper this season in the absence of Tom Clarke, was injured in the latter stages of Tuesday night's 1-0 defeat at Derby.
North End revealed the Irishman had since had an operation and would be out for 'some time'.
“As I described him after the game on Tuesday night, Greg is a ‘warrior’ – as illustrated by the fact he wanted to carry on despite having done the damage that now requires an operation - and I have no doubt he will be back fitter and stronger before very long and our medical team will work closely with him to get him back with us.
“Whilst we are disappointed to lose Greg, this gives other players in the squad an opportunity to show what they are capable of and we look forward to seeing them compete for a starting shirt in his absence.”
Only this week, Cunningham was named in a provisional 39-man Republic of Ireland squad for the forthcoming World Cup qualifiers against Georgia and Serbia.
Teenager Josh Earl took Cunningham's place at left-back for Saturday's Deepdale clash against Reading, with Kevin O'Connor named on the bench.