Santos started his first Premier League match of the season this weekend as the Gunners slipped to their second defeat of the season against Norwich City.
Santos revealed that he is not used to missing out on regular first-team football but insisted that he is ready to fight for a starting berth.
He told the club's official website: "Of course it is hard not playing. At every club I've been at I've always played regularly.
"It is difficult to be on the bench, but we are a team and this is a very healthy competition. We are always talking about it before and after training.
"Kieran is good friend and an exceptional player, and I know I have qualities too. I'll just keep working hard so I can be back on the pitch regularly."