The Blues have been hit by a busy schedule of fixtures due to their continued involvement in the Europa League and the FA Cup in addition to Premier League duties, resulting in them playing eight matches in April alone.
However, Ivanovic insists that his side will not be using that as an excuse and that they need to treat every match from now on as a cup final.
"In this stage of the season the number of games cannot be an excuse. You have to play every game like a final and we did that [against Sunderland] in the second half," Ivanovic told the club's official website.
"At half time we said we needed more energy and more intensity and our first goal was very important to give us the confidence and energy to do that. It is true we were under pressure and we didn't play at the level we needed to at the start, but we found a way to win.
"Sunderland changed their manager and a lot of things for his first game and we conceded a goal from a set piece. Especially when you concede in the first half at home it can be difficult to change the game, but we did it and we are happy about that. This result was an important three points and we are in a good way and we have to carry this on to the end of the season."
Chelsea are currently embroiled in a battle for a Champions League spot next season, sitting third in the Premier League table, two points ahead of fifth-placed Arsenal.