The Premier League side beat the French champions 2-0 to progress on the away goals rule, with Demba Ba scoring inside the final five minutes.
The manager told ITV Sprot: "I didn't go to the corner flag to celebrate. I went to tell them the changes we had to make. There were three minutes plus extra-time left and the way we were playing was too risky. I wanted Demba Ba to play in front of the defenders and Fernando Torres to defend Maxwell. I tried to use them in different jobs.
"I think we did enough at beginning of the second half to score before we did. The contradiction of what they are and what they wanted to do. In the second half it was pure ball possession. But it was difficult for us to penetrate. We did it in training yesterday, with three different systems, all of which we used. The players knew what they had to do. Demba Ba made a crucial finish for us.
"It was very much deserved that the team that tried to defend was punished. The team that played with their heart deserved to go through."
Chelsea have reached the last four seven times in the last 11 seasons.