The Blades have taken Black on a months loan and should start at Wigan Athletic tomorrow as injury's weaken the side.
Neil Warnock told sufc.co.uk; "It wasn't until late on Thursday night that Palace finally agreed to let us have him for a month. We've only taken him on the assumption that he can play in the cup on Tuesday.
"We are delighted to have him in the squad at a time when it is decimated by injury, especially with Andy Liddell not being available for another three weeks.
"I've been after Tommy on a few occasions previously, he is a direct wide player, who can play in a few positions," added Warnock.