Martin has produced a string of impressive performances this season to replace the experienced Steve Phillips between the posts.
And Davis says competition for the role is healthy with England youth international Ben Garratt in the ranks as well.
"Alan is the number one at the moment and he is like anyone else, if he plays well then he will stay in the team," Davis told the club's official website.
"I have always been fair with that and that is why Alan didn't play at all last season because Steve was in such good form and deserved to play.
"Now it is the other way round and Steve will be determined to get back in because he has been a regular for the majority of his career.
"Alan has come in and done consistently well and we have two good goalkeepers behind him as well because Ben is a promising young goalkeeper who has improved with the coaching he has received from Steve."