The 19-year old right-back has been battling a hip injury in recent months and could miss the first portion of the new campaign if he is forced to undergo surgery.
"Sam's got a hip problem," Leeds boss Brian McDermott told LUTV. "He had an injection last week and we'll have a look at it over the next two or three days, but there's a possibility that he'll need an operation.
"We don't know yet, but that could put him out for a period of time. We'll know within the next week and it's a shame for him, but he's only 19 and if he has to be out for a while, we have to do the right thing by Sam.
"He's a good guy and a very, very good player. We'll wait and see."