Sheffield United boss Paul Heckingbottom confirmed the deal to sign Cameron Archer will not be completed in time for Sunday's home Premier League game against Manchester City.
The Aston Villa striker completed his medical on Thursday after a reported fee of £18million was agreed between the two clubs.
When asked if the 21-year-old could make his debut this weekend at Bramall Lane, Heckingbottom said: 'No, the deadline was today.
'It's out of my hands, I don't know. It's pointless me saying it's not happening. I hope it's happening.