Ferdinand admits Man Utd yet to hit top gear
They have already played six of last season's top eight in their opening 10 matches this term - and beaten four of them.
Ferdinand said: "Chelsea did early in the season, they were playing well.
"We haven't hit a purple patch yet but that's what we are searching for. We played quite well against Arsenal but as far as getting it all in one package in the 90 minutes, we are still aiming for that.
"If you were in our changing room after the game you would have thought we'd lost the way the mood was. Are we top to stay? Let's hope so."