The England fullback admits he's desperate to win a first Premiership winners' medal with Chelsea this season.
He told the News of the World: "I still think there will be a long way in the title race regardless of the result of this game at the Emirates.
"There'll be no complacency from Chelsea - not until it's the end of the season and we are lifting that trophy.
"United always come strong towards the end of the season but hopefully we can get a good lead going into the New Year.
"Any squad is going to miss players of the quality of Essien, Drogba, Mikel, Kalou at the Africa Cup of Nations. We have got a stronger squad than people think but of course we'll miss the likes of Drogba."