Andre Villas, Jose Mourinho's right hand man, watched the win over Cambridge and Boxing Day draw with Chester.
The contrast between the two side's is immense, with the London side worth hundreds of millions - while United's side on Saturday hasn't cost a penny in transfer fees.
He warned Blues fans not to expect an easy win, telling Chelsea's official website: "For a League Two team they have good organisation. The principles are direct football, but direct football with some basics and quality.
"They're not a team who wants to drop back and defend, they play with some space behind. Goalkeeper Paul Musselwhite obviously has experience and he's good with his feet, confident upfield.
"The guy who impressed was Beagrie, with his experience. In one to ones he can still beat defenders, in attack Hayes has some mobility and some good movement.
"Sparrow is also a good player, and can play inside midfield or wide right. He has some quality, and inside can go one on one."