David Weir has confirmed he is still establishing a squad that will be competitive in League One this season.
The Blades boss was encouraged by Sean McGinty's debut against Colchester United and speaking ahead of Saturday's trip to Bradford City, Weir says places in the team are up for grabs in the immediate future.
The Gaffer said: "Marcus (Williams) didn't feature against Colchester United because Sean McGinty deserved a chance in the first-team environment.
"Sean has done very well in training and it is important that the lads understand that if they perform during the week they will be given an opportunity on a Saturday.
"He did very well, athletically the lad is fantastic and he will only improve. Obviously there is room for improvement like there is with all the players.
"For a debut at Bramall Lane in front of big crowd he really impressed me."
Weir continued: "I am still analysing the squad and within reason I have to give people a chance to make themselves a regular.
"I won't change everything every week, but at the moment I have to see who can do what in certain positions and assess where some of the other lads are best suited.
"We are right at the beginning of something here and it isn't all going to all happen overnight, I have to be clear in what I want and make the right judgments accordingly."