The Blues are currently top of the Premier League with six wins and a draw from their opening seven matches. Their only dropped points came against QPR, in a match that directly followed an international break.
That was the fourth time in seven games the Londoners have dropped points in a match after international fixtures.
In-form Tottenham lie in wait next weekend, before a Champions League trip to Shakhtar Donetsk and back-to-back games against Manchester United in the Premier League and Capital One Cup.
Ivanovic has warned his team-mates they will have to hit the ground running when they return from their respective national squads if they are to avoid another international hangover.
"The international break is a good time to enjoy our position but there is a very important period coming up for us after the break," said the Serbia defender.
"It's always very difficult to play the game after the international break, but especially when it's big opponents like Tottenham away.
"This game will be decided by things like when you are back from your international duty and how tired you are - the small details. So it's going to be tough for us."