United have four trialists currently at the club, but Football League rules dictate they cannot play competitive matches without first agreeing to sign a registration document.
The way round this is to enter into a pay-as-you-play agreement with the trialists.
Jermaine Wright is the only fit senior central midfielder in the squad while Danny Pugh is the only recognised left-sided player on the books.
Simon Walton will come into contention if Matthew Spring fails to shake off a groin problem and Leeds are being linked with West Brom's Sean Gregan but chief operating officer Shaun Harvey today confirmed that United are playing a waiting game in their bid to make additions to the squad.
Said Harvey in the Yorkshire Evening Post: "Enquiries have been made with clubs in relation to the availability of certain players. In certain circumstances we're waiting until clubs finalise their squads and make decisions on who they are willing to release. We have to be sure that any signings are right for Leeds United in the long-term. We are signing players for a number of seasons, not just one game."