Sheffield United trialists Silvio Spann and Jan-Michael Williams have not gone on the pre-season tour to Ireland because of work permit restrictions.
The duo are expected to feature in some of the reserve team games next week while the first-team are in Ireland.
Boss Bryan Robson told BBC Radio Sheffield: "There are work permit issues that are ongoing.
"So we are just going to assess these two lads as they go on and then later on we can make a decision."