"He is coming along but his test will come when we put him on the football field," he said.
"Maybe in two or three weeks time we will know better when he goes into football training and does twists and turns, and starts kicking a ball and we see what reaction we get from that.
"I don't think he will be playing by then, not in two or three weeks time.
"It's still too early to put a date on the calendar because we don't have the knowledge we would like about this type of injury particularly with a player of Roy's age."
Keane had surgery on his troublesome hip early in September and Sir Alex said: "Freddie Ljungberg who had a similar operation and is much younger, was out for three months."