Crewe are likely to be without in-form winger Byron Moore for their game against table-topping Leyton Orient on Saturday.
Moore, who played a key role in the win against Tranmere last weekend, suffered a flare-up of a recurring quad injury in the same game.
Crewe boss Steve Davis told the club's official website: "Byron is a major doubt again.
"His quad is troubling him again and he hasn't been able to train much this week.
"His scar tissue in the muscle had healed for him to play against Tranmere last weekend, but it re-opened and has troubled him again."