"It will be a beautiful battle of nerves now the final straight is starting," Ranieri told Sky television after goals by Daniele De Rossi and Luca Toni sank Inter.
"We are in good shape, both mentally and physically. The lads think we can do it. It won't be downhill. The remaining matches will all be difficult and we must be humble like we were tonight."
NEWS:Toni goal topples Inter
Ranieri has transformed a side of expected also-rans into title challengers after replacing Luciano Spalletti at the start of the season when they were in disarray.
Saturday's home victory over Inter and Jose Mourinho, with whom Ranieri had a series of verbal tussles when he was in charge of Juventus, extended Roma's unbeaten run in the league to 21 games.
Inter's Diego Milito, whose goal briefly levelled the score at 1-1 before Toni struck in the 72nd minute, said the champions would attempt to bounce back.
"We are serene although bitter about the defeat," the Argentine forward said. "We are looking forward. We'll try to win the upcoming matches. We are still top."
Mourinho did not speak to reporters after the match, continuing a month-long media boycott before and after Serie A games.
FEATURE:Ranieri's relaxed Romans reap rewards
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