Argentina defender Marcos Rojo dislocated his shoulder in Manchester United's 1-0 defeat at Manchester City on Sunday, their manager Louis van Gaal confirmed.

"His shoulder is out," the Dutchman told reporters. "We don't know how long that will take. I have to wait until Monday. But he shall not play against Crystal Palace (on Saturday), I don't think."

Rojo, who joined the club from Sporting Lisbon in August, fell heavily in a collision eight minutes into the second half and had to be replaced by teenager Paddy McNair.

Shortly afterwards, City's Sergio Aguero scored the only goal of the Premier League derby.