Atletico host the Champions League holders in the first-leg of their round of 16 tie.
And Arias knows he'll face a test against Liverpool ace Sadio Mane: "He is a difficult player. I don't know if I'm going to play or not, but if I have the opportunity I want to do it as usual, giving everything of myself to contribute to the team.
"I already had the opportunity to face Mané in the World Cup, we were in the same group and I know the conditions he has, how good he is and how complicated the game is going to be.
"But we have team and players to face the match."
The Argentina international also said of Diego Costa's availability: "He is important. We all want to be well, contribute to the team and the players who return from injury have the desire and the strength to want to go out and show this.
"Costa is a great player, has a lot of experience, brings a lot to the team and helps a lot of the new players. It's good to have him back."