Jose Mourinho's side were humiliated on their previous visit to Stamford Bridge, losing 4-0 in October, but have lost only twice in all competitions since.
"It will be a tough game," the Belgium international said.
"Obviously we lost there a few months ago, but now it is the FA Cup and we will see what happens.
"It will be tight, I think. It is the FA Cup, it is one game.
"They are top of the league, they have confidence, they have great players, but we will show our quality there and see what happens.
"Of course they are confident but let's go there and see what we can do."