Januzaj made an electric introduction to his Old Trafford career, scoring twice on his first Premier League start at Sunderland in October and impressing many with his tricky wing play.
But the 19-year-old has not played in United's three games since their 3-0 home defeat to Liverpool, missing out on the matchday squad altogether for last Tuesday's loss to Manchester City.
United host Aston Villa on Saturday before a crucial UEFA Champions League quarter-final first leg against Bayern Munich at Old Trafford, and Moyes insists the winger is still a big part of his plans.
"I think Adnan has played an incredible amount of games for a 19-year-old," he said.
"We have to be mindful of that. We have seen signs in training that we have to be careful what we do with him.
"He is a great talent and he is someone we know will go a long way at Manchester United. But we are just being careful with him.
"We have to do the right things and he has played a lot of football."
