Michael Carrick admits he doesn't know if Manchester United defender Matthijs de Ligt will play again this season as he struggles with a "difficult" back injury.
De Ligt remains sidelined as third-placed United head to Bournemouth on Friday looking to step up their bid to qualify for the Champions League.
The 26-year-old centre-back hasn't played for United since November 30 against Crystal Palace.
"He's obviously trying to work towards getting back, but it's just the back issue really that's proving difficult," Carrick said.
"We'll keep working as hard as we can to get him back as quick as we can."
Asked if there was a chance he would not feature for United for the rest of the campaign, Carrick said: "Honestly, it's difficult to say just because it's taken that much time.
"I can't give you any more on it really. It's one of those things with backs that sometimes you think it's all right and then all of a sudden it's not quite right.
"We're just kind of being patient and working through it. We'll just have to see. We'll obviously give him time, but trying to get him back as quick as we can, but it's really difficult to say.
"I'm not trying to hide anything. Literally at the moment we don't know so we'll have to wait and see."
De Ligt's injury has put his chances of going to the World Cup with the Netherlands in doubt, leading to questions over whether he might even need surgery.
"I don't want to get into that at this stage," Carrick said of a potential operation.
"I think we'll obviously try and do whatever we can to help Matta and help get him back and whatever that takes."