The cup holders face Manchester United in the quarter-finals on Sunday.
The 30-year-old goalkeeper told Chelsea TV: "The games are coming thick and fast. We won't have much time to prepare, but we'll get a little bit of rest and hopefully we'll have a good performance on Sunday.
"They are the favourites for the game, but it's the FA Cup and in the FA Cup not every time do the favourites win. We're still the holders, so we'll try to keep our trophy as long as we can."
Chelsea knocked Manchester United out of the Capital One Cup earlier this season.