from The Guardian
"We will have to see what the damage is in the morning but his [Javier Hernández's] leg is very numb and he could be out for a couple of weeks."
As Sir Alex says, we'll see. He was pretty critical of his own players, including Wayne Rooney, in the interview and seemed to be reaching a bit to keep the motivation high. I would expect Hernandez to be back sooner rather than later, but we'll see.