The third-placed Blues are currently a point clear of Liverpool, who went down 2-1 at Manchester City on Boxing Day, but Ivanovic is determined to widen the gap.
The Serbia international said: "It's going to be a very important game for us, one of the deciding games this season.
"We must be ready for the big fight. Our team likes to play big games and big challenges.
"I hope we're going to be ready for Liverpool, because it's a massive, massive game for us. It's very important for this part of the season to play defensively well.
"We have done in the last two games and it's good for us. We have to keep going. We have to defend as a team. For us it's very important to keep on this way and to try to fight as a team."
Chelsea manager Jose Mourinho said: "Every game is hard. The difference is some teams are bigger. Bigger name, bigger impact: Man City-Liverpool, Chelsea-Liverpool, Chelsea-Arsenal.
"But every game is difficult. The last two matches we played (at home), Swansea and Crystal Palace: 1-0, 2-1. You have to give everything to win matches."