Louis van Gaal has described Manchester United's current injury problems in defence as being a "disaster" after seeing Marcos Rojo stretchered off against Manchester City this afternoon.

The Argentina international required an oxygen mask in the 1-0 defeat at the Etihad Stadium following a challenge with Martin Demichelis shortly before the hour mark.

To make matters worse for United, Rafael da Silva missed out due to a knock sustained in training, while Chris Smalling will now serve a one-match ban after being dismissed in the derby game.

Van Gaal revealed that he is still awaiting news on Rojo's injury, but he does not expect him to feature again for the club this side of the international break.

"We have to wait and see," BBC Sport quotes the Dutchman as saying. "I am not a doctor. Maybe tomorrow I know more but I don't think he will play against Crystal Palace.

Michael Carrick and Paddy McNair were introduced to shore up an unfamiliar backline, and Van Gaal was happy with their showings.

"Michael Carrick was very good, as well as Paddy McNair. I am pleased they showed that but it is disaster - so many defenders are injured and you have to play every week with a different defence."

Today's defeat leaves United 13 points adrift of Premier League leaders Chelsea.