United are at Old Trafford tomorrow.
Ferguson said: "Chelsea have brought in Oscar and Hazard, two similar type players, I think. They're adapting to having these players with (Juan) Mata also.
"They're in behind the front player all the time and it's not an easy system to deal with. It's an interesting formation and we just have to find a way.
"With (Didier) Drogba they always had that alternative route. They could play it long or through midfield, but now it's straightforward. It's midfield all the time.
"Strong squads, particularly Chelsea and ourselves in terms of recent history, will always guarantee we will be able to handle the number of games you have to play."