Ahead of Saturday's League One clash with Yeovil Town, Chris Morgan says the current injury situation at Bramall Lane means several shirts are up for grabs.
With Matt Hill joining Neill Collins and Shaun Miller on the sidelines for the foreseeable future, boss Danny Wilson moved quickly in the transfer window to bring in Danny Higginbotham and Jamie Murphy from Stoke and Motherwell respectively.
But Morgan says there are still openings for players to stake a claim for a regular starting berth.
He commented: "Marcus (Williams) and Darryl (Westlake) are both able deputies for Matt (Hill) and we also have Callum (McFadzean) who can play at left back.
"It is down to whoever the manager picks to take the opportunity with both hands. It is an old cliché but it really is a case of if you perform you keep the shirt."
Morgan, who coaches the U21s at Shirecliffe, also believes a number of youngsters will continue to be given their chance to shine in the first team, sighting the full debuts of Terry Kennedy and Elliott Whitehouse as prime examples.
The former skipper added: "The only way to see if these youngsters are ready for the first team is to play them, you can watch them in training and in U21 matches but only when they play on a Saturday afternoon do you get a true reflection.
"The same questions that are being asked now came when the likes of Harry (Maguire) and George (Long) first broke into the first team.
"Both lads have been lucky to have had long stints in the team, but they have been given that chance because of the consistency of their performances.
"Terry (Kennedy) and Elliott (Whitehouse) let nobody down at Doncaster Rovers and the Gaffer showed he has no fear about throwing these lads in the team. We know what they can do, the only thing they lack at the moment is experience, but you are only going to get that through playing."