The 52-year-old, who grew up in the Italian capital and played for Lazio's city rivals AS Roma, insisted that his thoughts remained focused entirely on Tuesday's match.
"Of course I'm pleased to be back here, but I can't afford to think about that at the moment. The important thing is that Chelsea play well," he told reporters on Monday. "Lazio is a very good squad. They played well at Stamford Bridge and I'm expecting them to play even better tomorrow.
"It's not just their players. It's the way they're organised. (Lazio coach Roberto) Mancini has put together a team that plays good football. I'm sure it'll be an interesting match."
Chelsea came from behind two weeks ago to beat Lazio 2-1 at Stamford Bridge -- a result that lifted the London club to the top of the group on six points, two ahead of Lazio and Sparta Prague with Turkish side Besiktas fourth on three.
But Ranieri denied that he would settle for a draw in Rome.
"My players know me well. They know my philosophy is always to go for the win," he said, warning of the pitfalls of trying to play safe in such a tight group.
"Initially, Chelsea and Lazio were seen as the favourites, but in these early stages it's a mistake to make up your mind about the strengths and weaknesses of the other teams," he said.
"Chelsea and Lazio have an edge over the other two, but they still have to prove it on the pitch."
Meanwhile, Chelsea midfielder Frank Lampard said the less experienced members of the squad were quickly learning to adapt to the different demands of European football.
"Tactically, the Premiership is probably the fastest in the world. The pace in the Champions League is slower, but the teams are more sophisticated," he said.
"The most important thing is this competition is to concentrate for the full 90 minutes. If you let it slip for just a moment you get punished, like we did against Besiktas."
Chelsea lost 2-0 at home to Besiktas in their second match in the group
