Fergie admits the 30-year-old is currently struggling with the most difficult time of his United career.
“He has not had spells like this since he joined the club,” said Ferguson.
“It is an unusual experience for him, but he will get through it I am sure of that.”
Ferdinand joined United from Leeds United in 2002 for almost £30million.
“Games will help Rio,” added Ferguson. “Missing games takes the rhythm away. Getting it back is the challenge now.
“I am sure he has taken the criticism on board.
“I don’t know whether it is over-confidence, but there has always been a casual part of Rio’s game since he was a kid.
“It has been an advantage to him at times. At others, particularly in his younger days, it was a weakness.
“But along with his development and maturity, it has brought about some outstanding form over quite a long time for us.”
He continued: “All players worry about their form if they are getting criticism. They have to. They wouldn’t be human if they didn’t.
“We all go through little phases where we have to correct our game or take it a step up. I am sure Rio will do that.”