The Hoops meet the Spaniards at the Vicente Calderon Stadium in the opening Europa League group stage match and goalkeeper Forster says Falcao's view that Atletico can hit a big score will be thwarted by a determined Glasgow outfit.
"If we turn up and play the way we know we can we can be confident," he said.
"That's just Falcao's (who won the Europa last season with FC Porto) opinion but I'm pretty confident we can go there and give them a good game.
"It helps to go in as underdogs and they might get a surprise when we turn up.
"We didn't play as well as we could have against Sion (in the play-off) but this is now a chance to prove our critics wrong and show what we can do on the European front.
"In a way we'll have nothing to lose.
"We want to show what a good club Celtic are and the supporters want us to go out and put on some good performances in Europe.
"It's important we do that and that's the challenge for us all."