The Blues are currently fourth in the Premier League but are level on points with fifth-place Tottenham Hotspur with four games to play in the campaign.
Ivanovic told the club's official website: "All season we have been under pressure, we can't relax for one game.
"It's always difficult, they are champions and they are playing at home, but we need the points for the Champions League.
"We have to get points from the next two games to secure it (Champions League qualification), and then it will be much easier to prepare for the final."
Chelsea take on Manchester United at Old Trafford later today.