Diego Simeone’s men go into the game trailing 1-0 on aggregate after their defeat at Camp Nou last week and face a Barca side who dispatched Elche 6-0 on Saturday.
Atletico were also victorious in La Liga action after two goals from Antoine Griezmann inspired them to a 3-1 win over Rayo Vallecano and Tiago is eager to take that momentum into the vital fixture at the Vicente Calderon.
"Barcelona are on fire and they seem to get better with each game they play,” the 33-year-old former Chelsea and Juventus player told reporters.
“But we are not scared of Barcelona. It is great to be able to play them.
“It is a great opportunity for us against world-class players. Messi and Neymar are really good and are in great form. We can only stop them as a team.
“It was important for us to win against Rayo and we have to use to momentum gained from this win and take it into Wednesday's game.”
Tiago also took time to praise summer signing Griezmann, who has hit his stride with seven goals in his last eight games after an initially slow start when he arrived from Real Sociedad.
"We are really pleased for Griezmann and his two goals,” said the Portugal international.
“He seems to put every chance away. He is very quick and skilled. You have to make the most of players' form and right now, Griezmann is giving us goals and good football.”
Third-place Atletico have 44 points from their first 20 Liga games and sit four points behind leaders Real Madrid having played a game more.
