The Old Lady was paired with the Blues in the Champions League last 16 draw on Friday.
“It’s a pleasure going back to England and play Chelsea,” Ranieri told Juventus Channel.
“We have to analyse their poor results against the big teams as they have had plenty of injuries.
“We cannot underestimate them at all, it will be a disaster for them if they don’t win it as they are billed to.
“They have the best players in the world and we have to make sure we are in top form when we play them.”