Ranieri's arrival as a replacement for Gian Piero Gasperini in the autumn sparked a run of seven straight league wins that thrust Inter back into Champions League contention in Serie A, but things have since gone awry in spectacular fashion.
Inter have not won in six matches in all competitions and, after a 4-0 humbling at Roma, their last two games have seen them beaten, at home, by relegation-threatened Novara and Bologna to leave them seventh in the Italian standings.
They are competing in the last 16 of the Champions League for the eighth season running though, and Ranieri has called on his players to rediscover the hunger that took them to European football's top prize as recently as 2010.
"Inter's run in the championship has been a bit strange, with ups and downs," said the former Chelsea coach.
"We had a very average start and then we got going. Now we're in another negative period, but fortunately we have the Champions League to kick-start us. This team needs adrenaline and stimulation to produce good performances.
"Inter aren't the only team in Europe going through a difficult period. We're far from the top of the league but with two or three victories, we can get closer to the leading group."
Speculation about Ranieri's future has mounted after club president Massimo Moratti was seen storming away from his seat before the end of Friday's 3-0 loss to Bologna, but Ranieri says he is only thinking about the job in hand.
"I don't think about what will happen after the match," he said.
"I never ask players to play for me but for the shirt they wear and for the club. I'm getting along well with the president at the moment and I feel calm.
"I'm not nervous; it's not in my character."
Ranieri has crossed paths with Marseille coach Didier Deschamps on several occasions, with the Frenchman's Monaco side memorably upsetting Ranieri's Chelsea in the semi-finals of the 2003-04 Champions League.
Ranieri went on to replace Deschamps when he stepped down as Juventus coach in the summer of 2007.
Deschamps has declared that Inter's recent pedigree makes them the favourites to go through and Ranieri said it was time for his players to prove their worth.
"I'll meeting Deschamps again with real pleasure—he's someone who I respect a lot," said the Italian.
"I heard Deschamps say that Inter are the favourites. That's fair because two years ago, we won everything (Serie A, the Italian Cup and the Champions League).
"Unlike Marseille, we're going through a difficult period, but we'll try to turn things around, starting tomorrow (Wednesday).
"The time is ripe for a reaction. It's a direct double-header. I'm expecting a well contested encounter, so it's a good time to react."
Three-time European champions, Inter were upset by Schalke 04 in the quarter-finals of last season's tournament.
(For more sports news and updates, follow Ahram Online Sports on Twitter: @AO_Sports)