Speaking to the CT at the club's weekly press conference, McPake said:"The gaffer likes as much competition as possible and as a professional you have to accept that.
"Even when you are in the team, you're always thinking about who's out injured and when they'll be back, but at the end of the day, it is down to you to prove you deserve their place.
"The manager said that before and he's done that with every position on the pitch - whoever plays well keeps the jersey.
"At the moment, it's me and Nathan at centre half, so if we keep recording clean sheets that will give the gaffer a headache when Ben comes back."