Spurs have twice faced the Stamford Bridge outfit in the Premier League this season and have twice been held to a stalemate. However, Modric admits that he expects a different approach from both sides in the cup.
"It's a great venue, a great pitch and the atmosphere is amazing," he said.
"This is a big game for us. We have faced Chelsea twice in the league and both finished with draws.
"We need to take the positives from those games and believe in ourselves. It will be a little bit different this time, cup games are different to the league, but we hope that we will reach the final."
Tottenham take on Queens Park Rangers at Loftus Road next weekend.