Louis van Gaal says several Manchester United players are at risk of injury as he ponders a team to face Sheffield United.
Phil Jones is definitely out of Saturday's third-round tie at Old Trafford, and Van Gaal is worried about losing further players ahead of two Premier League away games in six days.
United go to Newcastle on Tuesday before a Super Sunday derby against Jurgen Klopp's Liverpool side, who are suffering from more injuries than most coming out of the Christmas programme.
Ashley Young is the player most at risk, according to Van Gaal, who does have Jesse Lingard available after a hamstring injury.
"Phil Jones is injured and a lot of players are in the red zone," the manager said at his pre-match press conference on Friday.
"Young was back in training this week. He is not injured, he is overloaded and in the red zone. More players are in the red zone and we have to decide if they can play against Sheffield United or not.
"Lingard has trained fully this week so he is ready."
Van Gaal has Will Keane and Adnan Januzaj back from loan spells, but the latter will not be available this weekend.
"He didn't play so many 90-minute matches in one season and he has to show his fitness in the second team," Van Gaal said.