A two-goal first-leg deficit must be overturned by Brendan Rodgers' men on Thursday night to book a place in the last 16 of the competition.
And with the Russian side looking to take advantage of away goals, Reina knows the challenge that lies ahead.
"It's up to both, players and fans," Reina told the club's official website.
"We have to show character from the beginning, especially in the first 15-20 minutes to get the people right behind us, but then they will lift us in the weak moments as they always do.
"The fact it is a night game makes it different. Supporters come to the game more excited. It's difficult to explain, but there's a different kind of atmosphere. There is no doubt the fans can make a difference."
Reina says the team's mentality is vital especially if Liverpool concede, meaning they will then be required to score a minimum of four goals.
The 30-year-old added: "The mentality of the players is different when you go into a game like this because you know you have to win by two or three goals.
"We have to make sure that we don't concede and if we do, we'll have to score four rather than three. I am really optimistic. It's a very difficult score to turn around but with the fans behind us I think the mentality will be spot on."