Brian Murphy is poised to sign a new six-month deal with Pompey.
Paul Cook has revealed the 32-year-old has agreed a contract that will keep him at Fratton Park until the end of the season.
He has done a lot better than some people give him credit for, he has kept 10 clean sheets. Imagine being a goalkeeper playing in a team and keeping 10 clean sheetsPaul Cook
The goalkeeper has made 20 Blues appearances and kept 10 clean sheets since arriving from QPR in the summer.
With ongoing injuries to Paul Jones (knee) and Michael Poke (hamstring), Cook has been keen to retain the services of Murphy beyond his initial six-month deal.
Now the Irishman is to remain and set to face former club Ipswich in the FA Cup.
Cook said: ‘We have agreed a new contract with Brian. The deal is until the end of the season.
‘He has done a lot better than some people give him credit for, he has kept 10 clean sheets. Imagine being a goalkeeper playing in a team and keeping 10 clean sheets?
‘He has made a mistake or two, of course he has, but what keepers don’t?
‘At the minute we have Michael Poke out with a torn hamstring and Paul Jones hasn’t played for three-and-a-half months, so we have no-one to cover.
‘We have to make sure our decisions are the correct ones in all positions.
‘Everyone’s place is under scrutiny at this club. You have got to make sure when you replace someone you do it properly.’
However, Cook admitted the option was there to enter the loan market for a keeper, if required.
He added: ‘I would imagine if I wanted to bring in another keeper then I could do.
‘At the minute we are in the place, as a club, where we could do that. And it is credit to the supporters who, by turning out against the likes of Crawley, allow the manager the money to spend.’