The Blues face United at Stamford Bridge.
Deco told The Sun: “The big difference between us and United is in attack. Drogba is enjoying a spectacular moment in his career and is superior to the front-line of United.
“For me, Didi will be the key – the star of the match, for sure.”
He added: “This match has a four-point value, an extra one for the blow to United’s morale because they also failed to beat Liverpool.
“If they fail in London they will need to think very much about things in the following days.
“Victories in classic matches like this always have enormous value.
“For Chelsea to begin November with a five-point advantage over United will be sensational.”
