Los Che host Atalanta behind closed doors in Valencia in their second leg on Tuesday, with the visitors boasting a sizeable advantage after their first leg triumph.
However, Celades pointed to previous European comebacks as a reason for hope, along with his side’s performance int he first leg which wasn’t reflected by the scoreline according to the Spaniard.
“We come into the game believing that we can do it,” Celades said.
“I said at the time - and I don’t think many people were convinced by it - that I think that the first leg result didn’t reflect what happened on the pitch.
“That is something that we can draw from as well. I think that we are capable of doing it, and if we don’t then it won’t be for lack of effort.”
Only last season, Liverpool, Juventus, Tottenham, Ajax Amsterdam and Manchester United produced remarkable second leg results in the knockout stages to win ties.
“It happens in football,” Celades said. “Many of us here have experienced it - be it playing in games or from watching them on the television.
“But it does happen. I think that tomorrow we need to have a very good game.
“Obviously we’re up against a very good side. We need to have a near-perfect game in order to go through, but we’re confident that we will be able to do it.”