Januzaj left United over the summer for La Real.
He told the Daily Mail: "Yes. That kind of stuff comes into your head. It was difficult... training sessions too. Under Ferguson, it was always intense. People wanted to win in training. It started to change.
"It was not the United we used to see winning games and winning trophies. Teams used to come to Old Trafford and be scared to play. I had the sense that some teams started coming to Old Trafford thinking, 'We can beat them today easy'."