Robson captained United to their first Premier League title under Ferguson in 1993, and again in 1994, and knows what it takes to win at the top level.
The former England skipper said: "The most amazing part of the boss' mentality is that everybody knows about the work he puts in around the club to build these teams, who have such desire and ability."
As for Manchester City, 'Robbo' commented: "There is definitely a danger there. City and United are getting all the plaudits because of the amount of goals they are scoring."
Ahead of United's showdown with Chelsea on Sunday, he added: "Chelsea have started steadily. I saw the Stoke game. They were a bit unfortunate not to get a penalty for a foul on Frank Lampard when the game was goalless. That could easily have won the game for Chelsea and then they would have made the same start as City and United.
"They have done well. They have great players. I like a few of the players they have brought in right at the last minute. You cannot discount them.
"Chelsea are a team who could go on a run and win six or seven games in a row. They have great experience in the squad. They will be up there challenging United and City this season."
United's former inspirational skipper knows that Rooney can still be the top man of the season.
Robson said: "I didn't think there was ever a danger of Wayne Rooney not getting back to where he once was. If you are a top player, you have dips in form. You are not going to play fantastic football all your career. That is all it was with Wayne.
"I don't think the ankle injury helped him going into the World Cup. Then he had a few problems in his private life. It does affect you. It weighs heavy. Thankfully he is over all that. He and his family are as well. He is playing his best football now, which is great for Manchester United and England."
PFA chief Gordon Taylor presented Robson with an award as the club's greater ever player this week, as voted by the players who were interviewed in the Manchester United book "19"
Robson was emotional about the award: "It is a great honour, especially when it comes from the players. I am not so sure about this poll, where I am above people like Bobby Charlton, Duncan Edwards. They were fantastic. It is a nice feeling."
• Tommy Docherty was speaking at the launch of Harry Harris' new book "19", published by Empire Publications. To pre-order for just £12, go to http://www.empire-uk.com/19.html