City currently have captain Vincent Kompany, Micah Richards, Gael Clichy and summer signing Martin Demichelis on the sidelines which has brought together 20-year old Nastasic and defensive midfielder Javi Garcia together at centre-back.
Nastasic is ware it is not ideal for City but knows that there has to be plenty of toiling to be done before their defensive depth returns.
"We made some changes in the team - in defence we played Javi and me. It was the first time and I think we did a good job, but I think I can play much better," he said in the wake of Saturday's 0-0 draw at Stoke City.
"In defence, it is difficult when we change the partnership every game. We did a good job but we need to play a lot of games, then it is looking better and better.
"For every team it is difficult to play here, for us as well. After the national team it is difficult because players are very tired.
"The manager (Manuel Pellegrini) is looking at who is fit for the game. We played with six different players. I think we played well but we need to improve and score a goal when we have the chance.
"This point is good for us and now we are looking forward."