Alex Morris says keeper Arthur Okonwko will have to fight to keep his place in the starting side just like everybody else.
The 20-year-old arrived on a season-long loan from Arsenal and was first choice, after Dave Richards suffered a finger injury.
But Richards, who made 35 appearances last season, is on the comeback trail and travelled with the squad to Salford City at the weekend.
Now Okonkwo, who stands at 6ft 6ins tall, will come under pressure for the place – and the manager says it is up to him to deal with it.
Morris said: “Arthur had a very composed start in the first two games, but he needed to have done better in the last two, in terms of some of the goals conceded.
“He is learning, and the challenge for him – now Dave Richards is nearing fitness – is that he has to hold down his place by performing well and being mistake-free.
“He has to fight for his place, which often isn’t the case in U23s football. That’s why Arsenal have sent him to us, to learn from those sorts of experiences.”
The boss admitted taking players on loan from big clubs is a balancing act.
He explained: “We have to always pick the best team to win the next game, because winning games is always the priority. And we want to keep good relationships with these clubs, Arsenal in particular who have been great with us recently, so it is a fine balance.
“We have to quickly instill into them things we need from them, because League Two football is so different to U23 football.”