By FOX Sports staff
Los Che head into Wednesday's tie at the Parc des Princes trailing 2-1 on aggregate, but are still alive in the tie thanks to Rami's 90th-minute goal in the first leg.
Although PSG remain favourites to progress to the quarter-finals, Rami believes his side must believe that they can overturn the deficit if they get off to a bright start.
"I'll be realistic; it will be hard," he told ParisFans.fr. "But this is an European competition and anything can happen.
"If we score a goal at the Parc des Princes, anything can happen and it will be game on."
Les Parisiens' preparation for the game has been far from ideal after they fell to a 1-0 defeat against Reims on Saturday, but Rami does not believe that will have much influence on Wednesday.
"I don't know if PSG's defeat to Reims at the weekend can work in our favour," the French international added. "But if they lose against us they'll be in big trouble.
"They are a very unpredictable team."
Valencia themselves warmed up for the clash with a 2-2 home draw against local rivals Levante.