Chris Wilder says the Blades have some injury concerns ahead of Saturday's Sky Bet Championship fixture against Derby County at Bramall Lane.
But speaking prior to the final game before the international break, the United manager predictably opted to keep his cards close to his chest and didn't reveal any names.
He commented: "We've got a couple of doubts, there are issues so I will keep that in house and give them as long as possible to prove their fitness.
"We want to give people extra recovery time, so that means we will select the team later than normal."
And there is mixed news on the recoveries of two key players, with Wilder adding: "Simon (Moore) is back out on the grass this week, he's been doing some movement work and handling so he's progressing nicely.
"But unfortunately for Richard (Stearman) it's going to be another six weeks or so, it was a bad one and we're going to be missing a big player for a decent amount of time."