"It's a long season so some of the players will get tired," Nani told MUTV.
"But we have a big squad and if we change one player it is not a problem because the players that come in do a good job.
"I am confident that if I play I can do well for the team. I have to wait for my opportunities and I knew that was the case when I joined. I don't see it as a problem.
"I am new at this club and players like Ryan Giggs have played for United for many years," he added.
"Giggs has a great history at this club. I just have to wait for my time to come and when it does I have to show that I can play well.
"I am OK and I feel settled at the club. I think I have improved a lot since I started. And as I get more games, more training and more time learning I will keep on improving as a player."