Neil Warnock has been thwarted in his attempts to lure three of his former players to Crystal Palace.
The former Sheffield United boss is keen on Blades trio Danny Webber, Nick Montgomery and Derek Geary.
All three are currently out of the first team picture at Bramall Lane but will not be allowed to leave while Kevin Blackwell looks to bring in replacements.
The United boss is also yet to assess the fitness of his returning international stars following their World Cup exploits over the last week.
"Neil knows the players, Palace are obviously struggling a little bit, and he wants to sign them because he knows what he will get out of them," Blackwell told the Yorkshire Post.
"But, we have got six games back-to-back very quickly so I will not, if I can help it, let anyone else go out of the squad.
"I dare not get caught with my trousers down - having a squad that can't cope.
"I have had one or two enquiries about my players but no-one will leave until after the players come back from international duty."
While Blackwell is standing firm in regards to allowing his own players to leave, he is facing a similar problem in his pursuit of former Blades star Michael Brown.
The midfielder is currently on the books of Wigan, but Latics boss Steve Bruce will not part company with any members of his squad until he is satisfied he has adequate cover for all positions.
"All the clubs we have been talking to have to wait until players come back from international duty," added Blackwell.
"There was nothing I could do about certain players until Friday morning or Friday afternoon.
"The loan situation is never quite in the hands of the club who wants the loan, it is in the hands of the club with the players."
Blackwell also confirmed that none of the players currently on the fringes of his side have submitted a transfer request.
"No-one has asked to leave and they all like coming to work," he said.
"The frustration will be that they want to play in the team and, as time goes on and players play less and less, I'm sure that frustration will grow."