Ranieri is now eyeing their Champions League second-leg clash with Chelsea and said: "Squad rotation has its risks, but we won.
"We must remember all the injuries we have had and how some players have been squeezed dry. I must thank Zebina, as I don't know how he managed to play for an hour.
"[Vincenzo] Iaquinta also did well against Lazio and he is getting back to fitness. When he is able to train regularly, he is an impressive striker."
"I am very happy with the performance of the defence. Now we'll have to see how everyone recuperates and take our throw of the dice against Chelsea.
"We know it will be difficult, but with the support of our fans and remembering English sides tend to struggle on their travels, we have to believe we can do it."