Rojo dislocated his shoulder against Manchester City at the start of November and it seemed at first that the Argentine could miss the rest of 2014.
But the defender was seen training with the first team last week and it appears the former Sporting Lisbon man has made a remarkable recovery after his initial prognosis.
“We have to wait and see until the last training session of course,” van Gaal explained during his press conference.
“It’s always difficult to say but we have good news, yes. You have to read between the lines.
“I have to train the last session and I live day by day at this moment. Maybe Rojo can come back in the 18.”
Rojo, 24, had a difficult start to life at Old Trafford but appeared to be settling into his centre-back role before his injury in the Manchester derby.
However, the news of Rojo’s impending return ahead of a busy Christmas period will be welcomed by United supporters, particularly given the current amount of injuries the club have in defence.