In last night's friendly, a scrappy own goal by Posh defender Russell Martin was followed after the break by a fine 25-yarder from substitute Darron Gibson.
Ferguson junior predicted: "Whoever finishes above United will win the league.
"They will take a bit of beating. It will be the usual top four, but I can't see anyone getting above them.
"He hasn't added to his squad yet and I don't know if he will - but the squad last season was the best anyway.
"The size and quality in depth in the squad is the difference."
"I thought we just edged it, and their goalkeeper made some very good saves.
"If Russell does that on Saturday I'll kill him. I'm glad that he got it out the way in a friendly.
"It was a good experience for my players. They had eight internationals out there in the first half.
"The second half petered out a bit, and we gave the ball away a bit too easily. When you do that with players of the quality United have, it takes you a long time to get it back."