Sheffield United manager Kevin Blackwell will not be taking a further look at the four trialist defenders who featured in the 1-0 defeat at Mansfield.
Athletic Bilbao's Ander Murillo, Greek Theo Berios, former Swansea and Peterborough full-back Tom Williams and Frenchman Williams Edjenguele all had run outs for the Blades at Field Mill on Saturday.
Blackwell said: "We shall not be continuing with them and they will not be joining us in Malta next week.
"They trained well and didn't let themselves down in the game, but we don't really think they're better than what we already have."
The Blades will be joined by a Polish full-back during their five-day tour of Malta this week.