Manchester United manager Louis van Gaal says a number of key players will not start against Liverpool tonight.
The Red Devils have to score at least two goals at Old Trafford to keep their Europa League hopes alive.
But they will have to do it without Ashley Young, Cameron Borthwick-Jackson and Bastian Schweinsteiger who are yet to fully recover from injury.
"They [Ashley Young and Cameron Borthwick-Jackson] are training now with us but you have to build up more than only one training session or two training sessions," van Gaal told MUTV.
"For example, Young and [Antonio] Valencia are out for a few months so it is not so easy to come back and that you can adapt to the rhythm of this level.
"Yeah [it's too early for them]. Too early also for [Bastian] Schweinsteiger [to start]. He has played two times 10 or 15 minutes, maybe he can play 45 minutes or 30 minutes dependable on the situation also on the pitch.
"I cannot say in advance but I try to do that of course. His impact was very big in the last game versus West Ham United and he was involved in the goal, I think. But, yeah, I have to cope with the fact when they're injured, they're not back at the moment they train one training session with you.
"Ashley Young has been two months away but Borthwick-Jackson is another case. He has been about three weeks away so that is different.
"For every player, it is difficult after an injury to come back in the team and I give always the example of Marcos Rojo, who was the exception because I didn't have other full-backs so I forced him to build up his capacity in the first team.
"He struggled, as you have seen, and I have given him 10 minutes, 20 minutes, 50 minutes, 70 minutes and then, at the end, 90 minutes, but he is now very tired yet he has to play maybe tomorrow.
"It is not easy for someone who has been out and maybe operated, so it is also a big transition for these kind of players.
"It is the same thing with Luke Shaw and with Wayne Rooney when he is coming back as he has already for three weeks [been in] a brace. You have to wait and see in the training sessions if he has that confidence to play a game or 20 minutes and that is difficult."