The Scot's Red Devils head for Stamford Bridge to take on the Premier League leaders - and the hosts will remain top of the table regardless of the result.
"Chelsea always had that alternative route of playing with Drogba up front," said Ferguson. "They could play it long or they could play it through midfield. Now it's straightforward. It's through midfield all the time.
"It's still not an easy system to deal with. Oscar and Hazard are similar type players. And with Mata as well they all play in behind the main striker. We just have to find a way of dealing with it."
On the sides' past meetings, Ferguson added: "We have actually played well in the games we have lost only to get bad decisions against us.
"Last season we did really well to rescue it after being 3-0 down and should have won it really. They could also have lost it though."