LEEDS newbie Tyler Roberts faces a lengthy spell on the sidelines after fracturing his leg.
The Welsh striker, 19, joined the Whites on deadline day from West Brom in a £2.5million move.
He was set for his debut this weekend against Bristol City before scans showed a crack on his shin.
Leeds and Roberts will consult with a specialist before announcing how long his injury will keep him out for.
New head coach Paul Heckingbottom said: "This is disappointing news for all concerned, especially for Tyler.
“However, with the help of the experienced medical team at Thorp Arch, he will come back stronger than ever.
“We would love to have Tyler involved as soon as possible but, particularly with our younger players, the club has a duty of care to ensure we don’t rush these situations because we expect Tyler to be an important player for us for years to come.”
Roberts had been nursing a knock since joining Elland Road last month.
He returned to light training at the end of last week and Heckingbottom admitted he was nearing a return.
The Leeds boss said: "He’s still not 100 per cent, so we did a light session today and he was involved so we will see how he reacts after that.
"He could play a part at Sheffield United.
"Possibly, like I say we've got a lot to factor in.
"Not only that, but for the long term as well. Tyler is someone I have seen play quite a lot, I spoke to his agent a number of times about taking him on loan myself.
"I know about Tyler, but I'm also about making people better and people earning places in the team, earning the right to play and people aren't ready."