"We have drawn with them a lot. I think that means there is great competition," Pinto told reporters at a press conference.
"A single detail could make the difference for one side or another. We leave with a result that's against us but we'll give our all in the return leg.
"Atletico have an advantage because of the score. The away goal is important. I wouldn't call them the favourites but they have an advantage."
Pinto will finish the season in the Barcelona goal following a long-term injury to Victor Valdes.