Inter won their first match in 10 games in all competitions when two late goals sealed a 2-0 Serie A victory at Chievo Verona on Friday and Ranieri was so overjoyed he had tears in his eyes.
While 2010 champions Inter are digging themselves out of a hole, Marseille have slipped into the mire with four straight defeats since their first-leg win and Ranieri sees an opportunity.
"Emotion is the most beautiful thing. I do this job to feel emotions, both positive and negative, but to tell the truth the positive ones are better," he said.
"I hope that on Tuesday against Marseille the San Siro will be full and the fans will be urging us on. It won't be an easy game, but we'll try. We have a chance. Let's try to see what we can manage to do with our fans behind us."
Ranieri's team selection will be hard to predict for counterpart Didier Deschamps after the Italian tried various formations in recent weeks to try to stop the rot.
He played three up front in the 2-2 home draw with Catania last weekend, when Inter's nervousness at home was again exposed as they went 2-0 down, but reverted to a 4-3-1-2 against Chievo with playmaker Wesley Sneijder coming in.
Substitute Giampaolo Pazzini replaced fellow striker Diego Forlan and previously out-of-form Esteban Cambiasso came on for Andrea Poli before Walter Samuel's and forward Diego Milito's late goals in Verona.
Marseille's reversal of fortune was unexpected given their 1-0 win over Inter at the Stade Velodrome last month had stretched their unbeaten run in all competitions to 16 matches.
"It was Didier's decision so that the players can be fully fit on Tuesday in Milan. I think we will be fine physically speaking," assistant coach Guy Stephan told the club's website.
Marseille: 30-Steve Mandanda; 2-Cesar Azpilicueta, 3-Nicolas N'Koulou, 21-Souleymane Diawara, 24-Rod Fanni; 17-Stephane Mbia, 4-Alou Diarra, 7-Benoit Cheyrou, 28-Mathieu Valbuena, 18-Morgan Amalfitano; 11-Loic Remy.
