Manchester United head coach Erik ten Hag has ruled Diogo Dalot out of Saturday's Premier League clash with Manchester City, while a late check will be made on Anthony Martial.
Dalot was substituted in the first half of the 3-0 win over Charlton Athletic on Tuesday night, with the Portugal international appearing to feel his hamstring before leaving the field.
The 23-year-old has only just recovered from the thigh problem that he suffered at the 2022 World Cup, but he will again be on the sidelines for the Manchester derby.
As a result, Aaron Wan-Bissaka, who has started the team's last three Premier League matches, is expected to be named in the starting XI at right-back once again.
There has also been some concern over Martial, who was not involved against Charlton.
The France international was substituted in the second half of the 3-1 win over Everton in the FA Cup last Friday, and he is also a doubt for the clash with Man City.
Ten Hag has said that Martial was able to train on Friday morning, but a decision on the striker's involvement against the English champions will not be made until Saturday.
"I think Diogo Dalot is not available and Anthony Martial, he trained his morning so we have to wait to see how he recovers from this training and if he's available. We will make the decision tomorrow," the Man United head coach told reporters during his pre-match press conference.
"It is a small thing in his leg [with Martial] and, if he is not available for tomorrow, it will be Wednesday [at Crystal Palace]."
Ten Hag was also asked about Casemiro during Friday's press conference, and the Dutchman was full of praise for the experienced midfielder.
"That is quite obvious (an impact). I said it from the beginning, this team, needed a No.6. Control, holding midfielder, he is so important. He is the cement between the stones," said the Dutchman.
"Defence, knows his position, points others into position, winning balls, duels mainly, in possession he can speed up the game. We are really happy to have him on board."
Man United are "close" to signing Wout Weghorst on loan from Burnley, meanwhile, but a deal has not yet been completed, so he will not be able to feature in the Manchester derby.
