United have a six-point lead over Chelsea with just seven games to go.
Ferguson told Sky Sports News: “Five wins, maybe even four (will be enough).
“Chelsea will drop points. Somewhere along the line they will drop something.
“We may drop something, but we’ve got it in our hands.
“We just need to keep our nerve. We did just that on Saturday, we kept our nerve and won comfortably at the end of the day.”