Harry Maguire (knee) and Chris Porter (hamstring) have both been rated as doubtful by Nigel Clough for Wednesday's Sky Bet League One with Peterborough United at Bramall Lane.
Maguire tangled with Hugo Rodallega in the first-half and subsequently limped off just after half-time, whilst United's goalscorer was withdrawn at the break after reporting a tight muscle.
Speaking after the game, Clough, who will be without skipper Michael Doyle against Darren Ferguson's Posh, says the duo will be monitored right up until the teamsheets are handed in on the night.
Clough confirmed: "Chris Porter had a very tight hamstring, if it goes he could miss the rest of the season, so he was withdrawn as a precaution.
"Harry Maguire got a kick on a nerve at the side of his knee. He wanted to give it a go in the second-half but he wasn't right and we knew he needed to get some treatment.
"Bob Harris came on at left-back with Matt Hill moving to centre-half and again both were excellent."
Clough is also adamant United are still very much in the FA Cup fourth round tie, after Sunday's stalemate. He added: "We have been to Villa Park and won, so now we look forward to a trip to Craven Cottage. Fulham will be focused on the league and proved that with 11 changes on Sunday, so who knows what will happen in the replay.
"It was a remarkable effort on Sunday, our workrate and desire meant we deserved a replay at the very least."