Crewe boss Dario Gradi says he is unsure whether versatile defender Carl Martin is capable of enjoying an injury-free season.
The 24-year-old has made just one competitive start for the club since signing almost two years ago, but he is currently fit and was even named as captain during the second half of their pre-season victory over Wolves on Saturday.
"Carl is fit and has come through two games. We just have to make sure he can stay fit," Gradi told the club's official website.
"I am not convinced yet that he can do that and become a serious contender for a place because he hasn't been with me a lot over the last two years.
"He is still in there and working hard to get himself fully fit. If he can then he would be a valuable asset to us because he has good attributes.
"I am playing him at centre-back at the moment because he is not fit enough to play at full-back. If he can remain fit then that would be a real bonus. A surprise bonus."