A virus has hit the Manchester United dressing room
A number of Manchester United players and staff have been hit with a virus, according to Louis van Gaal.
In addition, Michael Carrick will not play again for Manchester United this season because of a calf injury.
Carrick has not played since suffering the injury against Manchester City on April 12.
It was hoped that the midfielder would return, but he has no chance of featuring in the final three games of the season, Louis van Gaal said.
"Carrick shall not play this season any more," the United manager told a press conference.
"We have to focus on next season for him."
Van Gaal revealed during the press conference that a number of his players are doubtful for Saturday's game at Crystal Palace after a virus swept through the squad.
"We have a virus in our dressing room," Van Gaal said.
"I have a little bit of pain in the throat. (James) Wilson also has had that for one week but is recovering now. Maybe he can be on the bench (at Palace).
"A lot of players are suffering (from it)."
The good news for Van Gaal is that defenders Jonny Evans (sciatica) and Marcos Rojo (adductor) are in contention for a place in the squad for the trip to London after overcoming their respective injury problems.
"Rojo is coming back but (I may) put him on the bench or something like that," Van Gaal said.
"Evans is a candidate for the bench but he needs match rhythm."
Luke Shaw is also available again after his recovery from a groin injury, Van Gaal said.
Van Gaal made his first signing of the summer on Thursday when he agreed to buy Memphis Depay from PSV Eindhoven for £25million.
Van Gaal has a good relationship with Depay after handing him his international debut for Holland in 2013.
The 21-year-old was also part of Van Gaal's World Cup squad, helping them finish third in the tournament following a semi-final elimination by Argentina.
Despite the fact that Depay has scored 21 goals for PSV this season, Van Gaal was reluctant to sign the player before the end of the campaign.
He would have preferred to get the deal done in June, but the 63-year-old said he had to sign the player now as Paris St Germain were also determined to sign him.
"I have been forced to sign him," the Dutchman said.
"I don't want to sign him before the end of the season. We have to focus on our games.
"When you sign a player you disturb the focus of your present group of players.
"The coming matches are very important for Manchester United and for all of the players. But because of the market, I must handle it (now) - because otherwise he would have signed for PSG.
"That is why I signed Memphis."
Van Gaal feels his close relationship with PSV and the forward, who was also linked with Liverpool, was key to sealing the deal.
When asked why he felt Depay was in danger of signing for PSG, Van Gaal said: "Because at that time he was not reached by me.
"I don't want to speak with players before the season has ended.
"I have also a feeling to my players. But now, because of the close relationship I have with PSV, I could handle it."
Van Gaal's immediate priority is returning to winning ways on Saturday at Selhurst Park.
The Dutchman has presided over three straight defeats, putting United's chances of Champions League qualification in jeopardy.
A few weeks ago United were being tipped as outside challengers for the title, but they are now 18 points shy of the summit.
Chelsea won the league last weekend with three matches to spare and Van Gaal declared his former apprentice Jose Mourinho a worthy winner.
The 63-year-old, who was Mourinho's boss at Barcelona, opened his press conference on Friday with a tribute to the Blues and their manager.
"I have sent him a (congratulatory) text already, but I don't know if the message has arrived because I know he changes his number a lot," Van Gaal said with a smile.
"But I want to wish my colleague Jose Mourinho and Chelsea congratulations on a well-deserved championship.
"When you see the statistics, you cannot doubt that they are the real champion."
United are nervously looking over their shoulders after their recent dip left them four points above Liverpool, who play at Chelsea on Sunday.
Van Gaal has no problem with Mourinho for allowing his players at least three days off following last week's win against Palace, which sealed the title.
"That is the privilege of every manager when you are champion," Van Gaal said.
"I gave my players one day off more (than usual) but for another reason to what Jose Mourinho did.
"I think that Jose Mourinho can decide that and that his team shall play and do their utmost best (against Liverpool), I think."